supplementary angles

plural plural-only

(geometry) A pair of angles that sum to 180 degrees.

Japanese Meaning

補角 - 2つの角の和が180度になる角度の組み合わせ

In the homework, I identified the supplementary angles and used their relationship to find the missing measure.

宿題で、和が180度になる2つの角を見つけ、その関係を使って欠けている角度を求めました。

Sense（1）

(geometry) A pair of angles that sum to 180 degrees.

A = 30° and A′ = 150°, so A and A′ are supplementary angles.