Digits, Grade 7, Volume 1, Homework Helper

3-6: Sum of the Angles in a Triangle

Key Concept

In any triangle, the sum of the measures of the angles is 180°.

A triangle angles labeled 1 2, and 3.

Part 1

Example Finding the Measures of Interior Angles of Triangles

Write and solve an equation to find the value of x.

A triangle with a right angle, an angle measuring 27°, and an angle measuring x°.

Solution

Write and solve an equation for the sum of the measures of the angles of the triangle to find the value of x.

table with 4 rows and 1 column , row1 column 1 , , row2 column 1 , 27 degrees plus 90 degrees plus x degrees , column 2 equals 180 degrees , row3 column 1 , 117 plus x , column 2 equals 180 , row4 column 1 , x , column 2 equals 63 , end table

The value of x is 63.


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Table of Contents

Digits, Grade 7, Volume 1, Homework Helper Unit A: Number and Operations Unit B: Expressions, Equations, and Relationships Unit C: Measurement and Geometry Unit D: Proportionality English/Spanish Glossary Formulas Math Symbols Formulas Measures Properties