Question

A triangle has the following three (A,B,C) internal angles; A = 2x + 5, B = 40°, 4x - 9. What is the measure of angle A?

Answer 1

∠ A = 53°

Explanation:

the sum of the 3 internal angles of a triangle is 180° , that is

∠ A + ∠ B + ∠ C = 180 ( substitute values )

2x + 5 + 40 + 4x - 9 = 180 ( simplify left side )

6x + 36 = 180 ( subtract 36 from both sides )

6x = 144 ( divide both sides by 6 )

x = 24

Then

∠ A = 2x + 5 = 2(24) + 5 = 48 + 5 = 53°