Noteables Interactive Study Notebook (26491.0K) - McGraw-Hill ...

9–4EXAMPLE Find Angle MeasuresKEY CONCEPTSum of Angle Measuresin a TriangleThe sum of the measuresof the angles in a triangleis 180°.PARK A city park is in theshape of a triangle. Find thevalue of x in the triangle.The three angles markedare the angles of a triangle.Since the sum of the anglemeasures in a triangle is, x° + 36° + 36° = 180°.36x36Use mental math to solve the equation.x + 36 + 36 = 180Write the equation.x + = 180 Add 36 and 36. THINK What measureadded to 72 equals 180?+ 72 = 180 You know that + 72 = 180.So, the value of x is .Check Your Progress Find the value of x.38˚BUILD YOUR VOCABULARY (pages 219–220)Eachof a triangle is a line segment.Line segments that have the sameare calledcongruent segments.A scalene triangle hascongruent sides.An isosceles triangle hascongruent sides.Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.An equilateral triangle hascongruent sides.228 Math Connects, Course 1