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°.
