Determine the measure of the vertex angle of the isosceles triangle.
a. 34°
b. 16°
c. 58°
d. 112°
d. Simply substitute x = 34 into the equation for the vertex angle, 3x + 10. The result is 112°. If you select a, you solved for the base angle. If you select b, the original equation was written incorrectly as x + x + 3x + 10 = 90.