Complementary and supplementary angles review

CCSS Math: 7.G.B.5
Review the basics of complementary and supplementary angles, and try some practice problems.

Complementary angles

Complementary angles are two angles with a sum of 9090 ^\circ. A common case is when they form a right angle.
For example, BXC\angle BXC and CXD\angle CXD are complementary angles in the following diagram:
Note that BXD\angle BXD must be a right angle because AXB\angle AXB is a right angle.

Supplementary angles

Supplementary angles are two angles with a sum of 180180 ^\circ. A common case is when they lie on the same side of a straight line.
For example, AXD\angle AXD and DXC\angle DXC are supplementary angles in the following diagram:
Want to learn more about complementary and supplementary angles? Check out this video.

Practice set 1: Identify complementary and supplementary angles

Problem 1A
What is the relationship between AXY\angle AXY and YXB\angle YXB?
All segments that appear straight are straight.
Choose 1 answer:
Choose 1 answer:

Want to try more problems like this? Check out this exercise.

Practice set 2: Find a missing angle measure

Problem 2A
If AOC\angle AOC is a right angle and mAOB=79m \angle AOB = 79^\circ, what is mBOCm \angle BOC?
Note: Angles not necessarily drawn to scale.
  • Your answer should be
  • an integer, like 66
  • a simplified proper fraction, like 3/53/5
  • a simplified improper fraction, like 7/47/4
  • a mixed number, like 1 3/41\ 3/4
  • an exact decimal, like 0.750.75
  • a multiple of pi, like 12 pi12\ \text{pi} or 2/3 pi2/3\ \text{pi}
\Large{^\circ}

Want to try more problems like this? Check out this exercise.