Can somebody help me?

Step-by-step explanation:

(a) In ∆DEF, DE=EF

So, it is an isosceles triangle,

m<D=m<F

Therefore, m<D+m<E+m<F=180°

=>m<F+120°+m<F=q180°

=>2m<F=60°

=> m<F = 30°

(b)All the angles are 60° ,so it is a equilateral triangle, therefore, all the sides are equal.

AB= 13

m<F = 30°

AB = 13

Step-by-step explanation:

For (a)

since the sum of interior angles in a triangle is equal to 180 and angle E is given as 120°

The sum of angle D and F is 60°

EFD is an Isosceles triangle and the measures of F and D is equal and 30° each

For (b)

Since the triangle ABC is an equiangular triangle all angles measures and side lengths would be same

if measure of BC is 13 the length of AB would also be 13