Find each angle measure.
(13-16)
find each value.
(17-20)

Question 15

This is an isosceles triangle, which means the base angles given are equal.

x^2 = 3x + 10

x^2 - 3x - 10 = 0

(x - 5)(x + 2) = 0

Set each factor to 0 and solve for x.

x - 5 = 0

x = 5

x + 2 = 0

x = - 2

Reject x = -2.

Angle D = 5^2 ir 25°.

Angle E = 3(5)+10 or 25°.

The total measure of the angles of any triangle is 180°.

So, angle F = 180° - 50°.

Angle F = 130°.