Exercise 1 Page 766

We have been given measures of the two angles of a triangle, 58 and 90. 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 x be the unknown measure of the third angle, we can create an equation to solve for the third angle.

58+ 90+ x=180

AddTerms

Add terms

148 + x =180

SubEqn

LHS-148=RHS-148

x = 32

The measure of the third angle is 32^(∘).