Question

LA and L B are vertical angles. If m/ A = (« + 15)° and m/B = (5x - 17)°, then find the measure of ZB.

Answer 1

∠ B = 23°

Explanation:

vertical angles are congruent , then

∠ B = ∠ A , that is

5x - 17 = x + 15 ( subtract x from both sides )

4x - 17 = 15 ( add 17 to both sides )

4x = 32 ( divide both sides by 4 )

x = 8

Then

∠ B = 5x - 17 = 5(8) - 17 = 40 - 17 = 23°