Pearson Geometry Common Core, 2011
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Pearson Geometry Common Core, 2011 View details
5. Parallel Lines and Triangles
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Exercise 4 Page 175

130-x

Practice makes perfect

We have been given the measures of the two angles of a triangle, x and 50. We will find the measure of the third angle using the Triangle Angle-Sum Theorem. This theorem tells us that the measures of the interior angles of a triangle must add to 180^(∘).

If we let y be the unknown measure of the third angle, we can create an equation to solve for the third angle.

x+ 50+ y=180
x+y=130
y=130-x

The measure of the third angle is (130-x)^(∘).