Angle and Segment Proofs

Two lines are perpendicular if they intersect to form a right angle (90°).

A right angle is an angle that measures exactly 90 degrees.

Two angles are supplementary if the sum of their measures is 180 degrees.

If $$\triangle ABC \triangle DEF$$ , then $$\triangle DEF \triangle ABC$$ .

If $$a = b$$ , then $$a + c = b + c$$ for any number c.

If $$a = b$$ , then $$a - c = b - c$$ for any number c.

If $$a = b$$ , then $$ac = bc$$ for any number c.

If $$a = b$$ and @@c eq 0 $$, then$$ rac{a}{c} = rac{b}{c}@@.

If point D is in the interior of $$\triangle ABC$$ , then $$m\triangle ABD + m\triangle DBC = m\triangle ABC$$ .

Two angles are complementary if the sum of their measures is 90 degrees.