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Vocabulary perpendicular lines vertical angles adjacent angles complementary angles supplementary angles parallel lines

Concept A

Example 1 A Find a Missing Angle Measure A. Jun is cutting a tile. Classify the relationship of  a and  b. Answer: The angles are complementary. The sum of their measures is 90°.

Example 1 B Find a Missing Angle Measure B. If m  a = 53°, what is the measure of  b? m  b + 53 = 90Write the equation. m  b + 53 – 53 = 90 – 53Subtract 53 from each side. m  b = 37Simplify. Answer: m  b = 37°

Example 1 CYP A A.They are complementary. B.They are supplementary. C.They are congruent. D.They are obtuse. A. Elisa is cutting a piece of fabric. What is the relationship between  a and  b? a b

Example 1 CYP B A.140° B.220° C.50° D.90° B. If m  a = 40°, what is m  b? a b

Example 1 CYP B pg. 592

Example 1 CYP B pg. 592

Example 1 CYP B pg. 592

Example 1 CYP B pg. 592

Example 3 Use Algebra to Find Missing Angle Measures pg. 593

Example 3 Use Algebra to Find Missing Angle Measures ALGEBRA Angles DEF and WXY are complementary angles, with m  DEF = 2x and m  WXY = 3x – 20. Find the measures of  DEF and  WXY. m  DEF + m  WXY = 90Complementary angles 2x + 3x – 20 = 90Replace m  DEF with 2x and m  WXY with 3x – 20. Step 1 Find the value of x.

Example 3 Use Algebra to Find Missing Angle Measures Combine like terms. Add 20 to each side. Simplify. Divide each side by 5. Simplify.

Example 3 Use Algebra to Find Missing Angle Measures Answer: m  DEF = 44° and m  WXY = 46° Step 2 Replace x with 22 to find the measure of each angle. m  DEF = 2xm  WXY = 3x – 20 = 2(22) or 44 = 3(22) – 20 or 46

Example 3 Use Algebra to Find Missing Angle Measures pg. 593

Example 3 Use Algebra to Find Missing Angle Measures pg. 593

End of the Lesson