Answer:
- If angle C is 90 degrees (def. of right angle) then the sum of angle A and B has to 90 degrees since angle A + B + C (90°) = 180°
Statements and Reasons:
3. Angle C is 90 degrees because of the definition of right angle.
4. Angle A + angle B + angle C is 180 degrees because of triangle sum.
5. Angle A + angle B + 90 = 180 because of substitution postulate.
6. Angle A + angle B is 90 degrees because of subtraction postulate. (subtract 90 from both sides from the equation above this step).
7. Angle A and angle B are complementary.
