If two angles are supplementary and one is twice the other, how do I find their measures?

Question

Test questions often ask about angles that add up to 180°. If one angle is twice the other, how do we figure out each angle?

Answer 1

Let’s define:

1. Smaller angle = x
2. Larger angle = 2x (since it's twice as big)

Together they add up to 180:

x + 2x = 180

3x = 180 → x = 60

So the angles are:

1. 60° and 120°

✅ Final Answer: 60° and 120°

🧠 Tip: Remember:

1. Supplementary = 180°
2. Complementary = 90°

🎯 Angle relationship problems love phrases like “twice,” “three times,” or “10° more than.”

Answer 2

You are given that two angles are supplementary.

The first step is to understand the meaning of "supplementary". Supplementary angles add up to 180° and can be adjacent to each other or non adjacent but together they make a straight angle.

Next, we're told that one angle is twice the other...so we can label one angle as "x" and the other as "2x" thus making the equation x +2x =180.

Combine like terms: 3x = 180.

Divide both sides by 3 (use the inverse operation).

So x=180/3

x = 60.

Therefore x=60° and 2x =2*60° =120°

Answer 3

A+B = 180

A =2B

2B +B = 3B = 180

B = 180/3 = 60 degrees = pi/3 radians

A =2B = 120 degrees = 2pi/3 radians