13.1 Angle Relationships

Complementary (They form a right angle.) Complementary angles have a sum of 90 degrees. (They form a right angle.) Are the following angles complementary? m<1 = 37° and m<2 = 43° ? 37° + 43° = 90° 80° ≠ 90° No they are not complementary

Supplementary (They form a straight angle.) Supplementary angles have a sum of 180 degrees. (They form a straight angle.) Are the following angles supplementary? m<1 = 121° and m<2 = 59° ? 121° + 59° = 180° 180° = 180° Yes they are supplementary

Are the following angles complementary, supplementary, or neither? m<3 = 98° and m<4 = 82° 98° + 82° = 180° Supplementary

Are the following angles complementary, supplementary, or neither? m<3 = 33.1° and m<4 = 67.9° 33.1° + 67.9° = 101° Neither

Are the following angles complementary, supplementary, or neither? m<1 = 54.65° and m<2 = 35.35° = 90° 54.65° + 35.35° Complementary

Find the missing angle measure 39° + x° = 90° -39° -39° 39° x = 51°

Find the missing angle measure 21° + x° = 180° 21° -21° -21° x = 159°

Find the value of x. Then find the unknown angle measure. 32° x = 37° 4x = 148°

Find the value of x. Then find the unknown angle measures. 3x° + 6x° = 90° 6x° 9x° = 90° 3x° x = 10° 3x = 30° 6x = 60°

Vertical Angles Angles that are opposite each other from intersecting lines 108° Vertical angles are equal to each other 72° 72° x° 108°

Find the value of x. 5x - 1° = 64° 64° 5x° = 65° (5x-1)° x = 13°

Find the indicated angle measures 25º 25° 1 3 m<5 = 180º - 112º 2 m<5 = 68º 4x° 7 6 4 9 8 m<7 = 180 - 4xº 112° 5