1.
Acute Angle: An acute angle is an angle whose measure is greater than 0 and less than 90
2.
Acute Triangle: An acute triangle is a triangle in which all angles are acute
3.
Altitude: An altitude of a triangle is a line segment drawn from any vertex of the triangle to the opposite side and perpendivular to that side
4.
ASA: If there exists a correspondence between the vertices of two triangles such that two angles and the included side of one triangle are congruent to the corresponding parts of the other triangle, the two triangles are congruent
5.
Bisector: A point, segment, ray, or line that divides a segment into two congruent segments
6.
Circle: The set of all points in a plane that are the same distance from a given point
7.
Complementary Angles: Complementary angles are two angles whose sum is 90
8.
CPCTC: Corresponding parts of congruent triangles are congruent
9.
Equilateral Triangle: An equilateral triangle is a triangle in which all sides are congruent
10.
Hypotenuse: The side opposite of the right angle in a right triangle
11.
Isosceles Triangle: An isosceles triangle is a triangle in which at least two sides are congruent
12.
Legs: The sides that form a right angle
13.
Median: A median of a triangle is a line segment drawn from any vertex of the triangle to the midpoint of the opposite side
14.
Midpoint: The point that divides a segment into two congruent segments
15.
Obtuse Angle: An obtuse angle is an angle whose measure is greater than 90 and less than 180
16.
Obtuse Triangle: An obtuse triangle is a triangle in which one of the angles is an obtuse angle
17.
Perpendicular: Lines, rays, or segments that intersect at right angles are perpendicular
18.
Right Angle: A right angle is an angle whose measure is 90
19.
Right Triangle: A right triangle is a triangle in which one of the angles is a right angle
20.
SAS: If there exists a correspondence between the vertices of two triangles such that two sides and the included angle of one triangle are congruent to the corresponding parts of the other triangle, the two triangles are congruent
21.
Scalene Triangle: A scalene triangle is a triangle in which no two sides are congruent
22.
SSS: If there exists a correspondence between the vertices of two triangles such that three sides of one triangle are congruent to the corresponding sides of the other triangle, the two triangles are congruent
23.
Straight Angle: A straight angle is an angle whose measure is 180
24.
Supplementary Angles: Supplementary angles are two angles whose sum is 180
25.
Vertical Angles: Two angles are vertical angles if the rays forming the sides of one and the rays forming the sides of the other are opposite rays
