AlgebraSection 3-4

Supplementary angles - Two angles are supplementary if the sum of their measure is 180.

Complementary angles - Two angles are complementary if the sum of their measure is 90.

Sum of the angles of a triangle - The sum of the measures of the angles in any triangle is 180.

Section 3-4 definitions cont.

Triangle - a polygon with three sides and three angles.

Equilateral Triangle - each angle’s measure is the same.

Isosceles Triangle - at least two of the angles have the same measurement.

Right triangle - has one angle that is 90 degrees.

Section 3-4Examples

The measure of an angle is three times the measure of its supplement. Find the measure of each angle.

X +3x = 180

4x = 180 4x/4 = 180/4 ( divide both sides by 4)

x = 45

Thus the measures are 45 and 3 x 45 or 135

Section 3-4Examples

The measure of an angle is 34 greater than its complement. Find the measure of each angle.

x + (x + 34) = 90 2x + 34 = 90 2x +34 -34 = 90 -34 (subtract 34 from both sides)

2x = 56 2x/2 = 56/2 ( divide both sides by 2)

x = 28

The measures are 28 and (28 + 34) or 62