Question

Parallelogram ABCD m/DAB = (5x+12) °
and
m/BCD= (7x - 28).

What is m/ABC?

Answer 1

∠ ABC = 68°

Explanation:

In a parallelogram

• opposite angles are congruent (equal ) , then

∠ BCD = ∠ DAB ( substitute values )

7x - 28 = 5x + 12 ( subtract 5x from both sides )

2x - 28 = 12 ( add 28 to both sides )

2x = 40 ( divide both sides by 2 )

x = 20

Then

∠ BCD = 7x - 28 = 7(20) - 28 = 140 - 28 = 112°

In a parallelogram

• consecutive angles are supplementary ( sun to 180° ) , then

∠ ABC + ∠ BCD = 180°, that is

∠ ABC + 112° = 180° ( subtract 112° from both sides )

∠ ABC = 68°