Question

If mA = 2x and mD = 9x + 15, then what is mA?

15°
20°
34°
30°

Answer 1

Explanation:

Because ABCD is a parallelogram, then ∠A = ∠C and ∠B = ∠D. In a parallelogram, all angles will sum up to 360°.

So,

∠A + ∠B + ∠C + ∠D = 360°

2x + (9x+15°) + 2x + (9x+15°) = 360°

22x + 30° = 360°

22x = 330°

x = 15°

Now, we know the value of x. Let's find the value of ∠A

∠A = 2x

∠A = 2 . 15°

∠A = 30°

The final answer is, ∠A = 30°