Question

Given: Isosceles Triangle DEF. The measure of vertex Angle D is four times the measure of each base angle E and F.

Find the measures of Angles D, E, and F.

Measure of Angle D =

degrees.



Measure of Angle B =

degrees.



Measure of Angle C =

degrees.

Answer 1

• ∠D = 120°
• ∠E = ∠F = 30°

Explanation:

The ratios of the measures of the angles are ...

D : E : F = 4 : 1 : 1

The sum of ratio units is 6, so each must stand for 180°/6 = 30°. Then the ratios of actual angles are found by multiply the ratio units by 30°:

D : E : F = 120° : 30° : 30°

Angle D is 120°; angles E and F are each 30°.