Video: Finding the Measure of an Angle Given Its Supplementary Angle’s Measure

Video Transcript

Find the measurement of angle 𝐷𝐵𝐶.

Here we have point 𝐷, 𝐵, and 𝐶. This is angle 𝐷𝐵𝐶. There are two angles in the given figure on a straight line. Angles on a straight line total 180 degrees. This means that angle 𝐷𝐵𝐶 plus 35 degrees equals 180 degrees. So we can use the inverse to help find the answer. We need to subtract 35 from 180 degrees to give us the measure of angle 𝐷𝐵𝐶. 180 degrees take away 30 degrees gives us 150 degrees. We’ve subtracted the 30 from 35. Now we just need to subtract the five. 150 subtract five is 145.

Angle 𝐷𝐵𝐶 measures 145 degrees.