2 Algebra Section 3-4Supplementary 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.
3 Section 3-4 definitions cont. Triangle - a polygon with tree 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.
4 Section 3-4 ExamplesThe measure of an angle is three times the measure of its supplement. Find the measure of each angle.X +3x = 1804x = 1804x/4 = 180/4 ( divide both sides by 4)x = 45Thus the measures are 45 and 3 x 45 or 135
5 Section 3-4 ExamplesThe measure of an angle is 34 greater than its complement. Find the measure of each angle.x + (x + 34) = 902x + 34 = 902x = (subtract 34 from both sides)2x = 562x/2 = 56/2 ( divide both sides by 2)x = 28The measures are 28 and ( ) or 62