### Home > GC > Chapter 11 > Lesson 11.1.3 > Problem 11-45

11-45.

Sum of interior angles = 180(*n* − 2) = 180(5 − 2) = 540°

Therefore, 90 + 4*x* + (8*x* − 10) + 90 + (6*x* + 4) = 540

*x*² + (*x* + 17)² = 25²

*x*² + (*x*² + 34*x* + 289) = 625

You can ultimately solve this problem by factoring.

*x* = 7

Note that because the figure is an isosceles triangle, two angles are equal to *x* + 4° and the remaining angle is equalto 46°, since it is supplementary to the angle of 134°.

*x* = 63°

(3*x* + 15) + (*x* + 9) = 180°