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Definition
An angle whose measure is greater than 0 and less than 90 (degrees). |
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Definition
A triangle in which all three angles are acute. |
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alternate exterior angles |
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Definition
A pair of angles in the exterior of a figure formed by two lines and a transversal, lying on alternate sides of the transversal and having different vertices. |
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alternate interior angles |
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Definition
A pair of angles in the interior of a figure formed by two lines and a transversal, lying on alternate sides of the transversal and having different vertices. |
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Definition
A perpendicular segment from the vertex of a triangle to the opposite side, extended if necessary. |
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Definition
A figure formed by two rays with a common endpoint. |
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Definition
The angle between a downward line of sight and the horizontal. |
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Definition
The angle between an upward line of sight and the horizontal. |
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Definition
A region bounded by two concentric circles. |
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Definition
A segment joining the center of a regular polygon to the midpoint of one of the polygon's sides. |
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Definition
A figure consisting of two points on a circle and all points on the circle needed to connect them by a single path. |
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Definition
The number of square units of space within the boundary of a closed region. |
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Definition
The average of two numbers. The arithmetic mean of the numbers a and b, for example, is (a+b)/2. |
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Definition
A line introduced into a diagram for the purpose of clarifying a proof. |
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base (of an isosceles triangle) |
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Definition
In a nonequilateral isosceles triangle, the side that is congruent to neither of the other sides. |
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Definition
Either of the two parallel sides of a trapezoid. |
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Definition
In an isosceles triangle or trapezoid, the angle formed by a base and an adjacent side. |
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Definition
To divide a segment or an angle into two congruent parts. |
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Definition
The center of the circle of which an arc is a part. |
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Definition
An angle whose vertex is at the center of a circle. |
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Definition
The point of concurrency of the medians of a triangle. |
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Definition
A segment joining two points on a circle. |
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Definition
An angle formed by two chords that intersect at a point inside a circle but not at the circle's center. |
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Definition
The set of all points in a plane that are a given distance from a given point in the plane. (That point is called the circle's center.) |
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Definition
A point associated with a polygon, corresponding to the center of the polygon's circumscribed circle. (The circumcenter of a triangle is the point of concurrency of the perpendicular bisectors of the triangle's sides.) |
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Definition
The perimeter of a circle. |
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Definition
A polygon each of whose sides is tangent to a circle. |
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Definition
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Definition
A line tangent to two circles (not necessarily at the same point)--called a common internal tangent if it lies between the circles or a common external tangent if it does not. |
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Definition
Two angles whose sum is 90 degrees (a right angle). |
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Definition
The intersection of two or more loci. |
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Definition
Two or more coplanar circles with the same center |
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Definition
The "then" clause in a conditional statement. |
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Definition
Lines that intersect in a single point. |
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Definition
A statement in the form "If p, then q," where p and q are declarative statements. |
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Definition
Angles that have the same measure. |
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Definition
Arcs that have the same measure and are parts of the same circle or congruent circles. |
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Definition
Segments that have the same length. |
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Definition
Triangles in which all pairs of corresponding parts (angles and sides) are congruent. |
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Definition
A drawing made with only a compass and a straightedge. |
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Definition
A statement associated with a conditional statement "If p, then q," having the form "If not q, then not p." |
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Definition
A statement associated with a conditional statement "If p, then q," having the form "If q, then p." |
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Definition
A polygon in which each interior angle has a measure less than 180 degrees. |
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Definition
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Definition
In a figure formed by two lines and a transversal, a pair of angles on the same side of the transversal, one in the interior and one in the exterior of the figure, having different vertices. |
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Definition
The intersection of a solid with a plane. |
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Definition
A quadrilateral that can be inscribed in a circle. |
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Definition
A segment that joins two nonconsecutive (nonadjacent) vertices of a polygon. |
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Term
diagonal (of a rectangular solid) |
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Definition
A segment whose endpoints are vertices not in the same face of a rectangular solid. |
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Definition
A chord that passes through the center of a circle. |
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Definition
The length of the shortest path between two objects. |
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Definition
Having all angles congruent. |
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Definition
Having all sides congruent. |
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Definition
An angle that is adjacent to and supplementary to an interior angle of a polygon. |
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Term
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Definition
The first and fourth terms of a proportion. In the proportion a:b=c:d, for example, a and d are these. |
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Definition
One of the polygonal surfaces making up a polyhedron. |
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Definition
The point of intersection of a line and a plane. |
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Definition
The fourth term of a proportion. In the proportion a:b=c:x, for example, x is this. |
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Definition
The portion of a pyramid or a cone that lies between the base and a cross section of the figure. |
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Definition
Either of the two means of a proportion in which the means are equal. Also called a mean proportional. |
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Definition
The side opposite the right angle in a right triangle. |
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Definition
The "if" clause in a conditional statement. |
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Definition
A point associated with a polygon, corresponding to the center of the polygon's inscribed circle. (The incenter of a triangle is the point of concurrency of the triangle's angle bisectors.) |
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Definition
An angle whose vertex is on a circle and whose sides are determined by two chords. |
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Definition
A polygon each of whose vertices lies on a circle. |
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Definition
A statement associated with a conditional statement "If p, then q," having the form "If not p, then not q." |
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Definition
A trapezoid in which the nonparallel sides are congruent. |
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Definition
A triangle in which at least two sides are congruent. |
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Definition
A quadrilateral in which two disjoint pairs of consecutive sides are congruent. |
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Definition
The sum of the areas of a solid's lateral faces. |
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Term
leg (of isosceles trapezoid) |
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Definition
One of the nonparallel, congruent sides of an isosceles trapezoid. |
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Term
leg (of isosceles triangle) |
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Definition
One of the two congruent sides of a nonequilateral isosceles triangle. |
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Definition
One of the sides that form the right angle in a right triangle. |
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Definition
A set consisting of all the points, and only the points, that satisfy specific conditions. |
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Definition
An arc whose points or on or outside a central angle. |
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Term
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Definition
The second and third terms of a proportion. In the proportion a:b=c:d, for example, b and c are these. |
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Definition
A segment joining the midpoints of the nonparallel sides of a trapezoid. |
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Definition
A segment from a vertex of a triangle to the midpoint of the opposite side. |
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Definition
A point that divides a segment or an arc into two congruent parts. |
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Definition
An arc whose points are on or between the sides of a central angle. |
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Term
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Definition
Two intersecting lines that are not perpendicular. |
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Definition
An angle whose measure is greater than 90 and less than 180 (degrees). |
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Definition
Two collinear rays that have a common endpoint and extend in opposite directions. |
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Definition
The point of concurrency of the altitudes of a triangle. |
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Definition
Coplanar lines that do not intersect. |
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Term
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Definition
A quadrilateral in which both pairs of opposite sides are parallel. |
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Definition
The sum of the lengths of the sides of a polygon. |
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Definition
Intersecting at right angles. |
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Definition
A line that bisects and is perpendicular to a segment. |
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Term
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Definition
A surface such that if any two points on the surface are connected by a line, all points of the line are also on the surface. |
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Definition
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Definition
A solid figure that has two congruent parallel faces whose corresponding vertices are joined by parallel edges. |
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Definition
An equation stating that two or more ratios are equal. |
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Definition
An instrument, marked in degrees, used to measure angles. |
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Definition
A solid figure that has a polygonal base and lateral edges that meet in a single point. |
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Definition
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Definition
A segment joining the center of a circle to a point on the circle. Also, the length of such a segment. |
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radius (of regular polygon) |
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Definition
A segment joining the center of a regular polygon to one of the polygon's vertices. |
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Term
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Definition
A quotient of two numbers. |
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Definition
A straight set of points that begins at an endpoint and extends infinitely in one direction. |
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Definition
A parallelogram in which at least one angle is a right angle. |
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Definition
A prism with six rectangular faces. |
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Definition
A polygon that is both equilateral and equiangular. |
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Definition
A parallelogram in which at least two consecutive sides are congruent. |
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Definition
An angle whose measure is 90 degrees. |
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Definition
A triangle in which one of the angles is a right angle. |
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Definition
A triangle in which no two sides are congruent. |
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Definition
A line that intersects a circle at exactly two points. |
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Definition
An angle whose vertex is outside a circle and whose sides are determined by two secants. |
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Definition
The part of a secant that joins a point outside the circle to the farther point of intersection of the secant and the circle. |
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Term
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Definition
An angle whose vertex is outside a circle and whose sides are determined by a secant and a tangent. |
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Definition
A region bounded by two radii and an arc of a circle. |
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Definition
A region bounded by a chord of a circle and its corresponding arc. |
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Definition
An arc whose endpoints are the endpoints of a diameter. |
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Definition
Polygons in which the ratios of the measures of corresponding sides are equal and corresponding angles are congruent. |
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Definition
Two lines that are not coplanar. |
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Definition
A perpendicular segment from the vertex of a pyramid to a side of the pyramid's base. |
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Definition
A parallelogram that is both a rhombus and a rectangle. |
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Definition
An angle whose measure is 180 degrees. |
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Definition
Two angles whose sum is 180 degrees (a straight angle). |
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Definition
A line that intersects a circle at exactly one point. |
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Definition
An angle whose vertex is on a circle and whose sides are determined by a tangent and a chord that intersect at the tangent's point of contact. |
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Definition
Circles that intersect at exactly one point. |
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Definition
The part of a tangent line between the point of contact and a point outside the circle. |
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Definition
An angle whose vertex is outside a circle and whose sides are determined by two tangents. |
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Definition
A mathematical statement that can be proved. |
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Definition
A line that intersects two coplanar lines in two distinct points. |
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Definition
A quadrilateral with exactly one pair of parallel sides. |
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Definition
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Definition
To divide a segment or an angle into three congruent parts. |
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Definition
The common endpoint of the two rays that form an angle. |
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Definition
The common endpoint of two sides of a polygon. |
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Definition
The angle opposite the base of a nonequilateral isosceles triangle. |
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Definition
A pair of angles such that the rays forming the sides of one and the rays forming the sides of the other are opposite rays. |
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Definition
The number of cubic units of space contained by a solid figure. |
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