Question

Two consecutive angles of a parallelogram measure 3x+42 and 9x-18. What are the measures of the angles?

Answer 1

The angles are 81 degrees and 99 degrees

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Step-by-step explanation:

Consecutive angles, aka adjacent angles, of a parallelogram always add to 180 degrees. They are considered supplementary.

(angle A)+(angle B) = 180

(3x+42)+(9x-18) = 180

(3x+9x)+(42-18) = 180

12x+24 = 180

12x = 180-24

12x = 156

x = 156/12

x = 13

We can then find the measure of each angle

• angle A = 3x+42 = 3*13+42 = 81
• angle B = 9x-18 = 9*13-18 = 99

Then notice that A+B = 81+99 = 180 to confirm the answers.