Congruent
when two parts of a geometric figure have the same measure
Corresponding
geometric items that are in the same position in different figures
Vertical angles
a must be equal to b.
Distance formula
Given two points (x1, y1) and (x2, y2)
Reflexive property of equality
This reason is used to help prove congruence when one side that is part of two triangles has a length that is equal to itself.
Acute angle
An angle that is less than 90 degrees. <B is acute
Right angle
An angle that is exactly 90 degrees. <B is a right angle
Obtuse angle
An angle that is greater than 90 degrees. <C is an obtuse angle
Scalene triangle
A triangle which has sides of three different lengths
Isosceles triangle
A triangle which has two side with the same length and one side that is a different length
Equilateral triangle
A triangle which has all three sides of the same length
Equiangular triangle
A triangle that has all three angles that measure the same (60 degrees each)
Linear pairs
Two adjacent angles which add up to 180 degrees (These angles are also supplementary.)
Complementary angles
Two angles which add up to 90 degrees
Supplementary angles
Two angles which add up to 180 degrees
Included side
A side that is between two angles in a triangle
In the figure, LM is the included side between angle L and angle M.
Included angle
An angle that is between two sides in a triangle
In the figure, angle N is the included angle between LN and MN.
Angle-Side-Angle (ASA)
DOES prove triangles congruent when two adjacent angles and the included side are congruent
Side-Angle-Side (SAS)
Pair 4 shows that when two adjacent sides and the included angle are congruent, the triangles are congruent.
Side-Side-Side (SSS)
When all three sides are congruent, the triangles may be said to be congruent.
Acute triangle
A triangle that has ALL angles LESS than 90 degrees.
Right triangle
A triangle that has exactly ONE angle that is EXACTLY 90 degrees. The other two angles are complementary.
Obtuse triangle
A triangle that has exactly ONE angle GREATER than 90 degrees.
Side-Angle-Side (SAS)
Two sides are given and the included angle in two congruent triangles
Angle-Side-Angle (ASA)
Two angles are given and the included side in two congruent triangles
Side-Side-Side (SSS)
All three sides are given in two congruent triangles.