Question

If two angles are supplementary and one of them is 30 , what is the measurement of the second angle?

A. 180
B. 90
C. 60
D. 150

Answer 1

Answer: Hello there!

If you have a line (with a plane angle of 180°) and a segment that cuts the line, the two angles generated by the line and the segment are supplementary, and the sum of them should be equal to 180°

if one of the angles is 30°, then the other angle should be:

180° - 30° = 150°

then the right answer is option D.

Answer 2

You just need to know the definition of suplementary angles. Two angles are suplementary if the sum 180°. So, you now can easily deduct that the unkonwn angle is such that when sumed to 30° the result is 180° => x + 30 = 180=> x = 180 - 30 => x = 150°. And the answer is the option D) 150.