Question

The sum of the angle measures of any triangle is 180 degrees. Angle 2 is twice the measure of angle 1. Angle 3 is 15 degrees less than the measure of angle 2. What is the measure of each angle?

Answer 1

39°, 78°, 63°

Explanation:

let ∠ 1 = x, then

∠ 2 = 2x ( twice the measure of ∠ 1 )

∠ 3 = 2x - 15 ( 15° less than ∠ 2 )

Sum the 3 angles and equate to 180

x + 2x + 2x - 15 = 180, that is

5x - 15 = 180 ( add 15 to both sides )

5x = 195 ( divide both sides by 5 )

x = 39

Thus

∠ 1 = 39°

∠ 2 = 2 × 39° = 78°

∠ 3 = 78° - 15 = 63°

Answer 2

Angle 1 = 39, Angle 2 = 78 , Angle 3 = 63

Explanation:

78/2 = 39

(Angle 2/2 = Angle 1)

78 - 15 = 63

(Angle 2 - 15 = Angle 3)

39 + 78 + 63 = 180

(Angle 1 + Angle 2 + Angle 3 = 180)