~ 7.2 ~
Adjacent Angles
Learning Targets
I can find unknown angle measures by reasoning about complementary or supplementary angles.
I can recognize when adjacent angles are complementary or supplementary.
Notes
If two angle measures add up to 90°, then we say the angles are complementary. Here are three examples of pairs of complementary angles.
If two angle measures add up to 180°, then we say the angles are supplementary. Here are three examples of pairs of supplementary angles.
Vocabulary
complementary
Complementary angles have measures that add up to 90 degrees.
For example, a 15° angle and a 75° angle are complementary.
supplementary
Supplementary angles have measures that add up to 180°.
For example, a 15° angle and a 165° angle are supplementary.
adjacent angles
Two angles are adjacent when they have a common side and a common vertex (corner point) and don't overlap. In regular English, adjacent means "next to".
Activities
2.1 Estimating Angle Measures
Estimate the degree measure of each indicated angle.
2.3 Is It a Complement or Supplement?
Use the protractor in the picture to find the measure of angles:
BCA
BCD
Explain how to find the measure of angle ACD without repositioning the protractor.
Use the protractor in the picture to find the measure of angles:
LOK
LOM
Explain how to find the measure of angle KOM without repositioning the protractor.
Angle BAC is a right angle. Find the measure of angle CAD.
Point O is on line RS. Find the measure of angle SOP.
Add to Your Notes
What does it mean for two angles to be supplementary?
Their sum measures to 180°.
What does it mean for two angles to be complementary?
Their sum measures to 90o.
If you know two angles are supplementary and you know the measure of one angle, how can you find the other?
Subtract the angle you know from 180o.
Assignment
Check Google Classroom!