All equilateral triangles are also isosceles triangles.

True

Step-by-step explanation:

Isosceles triangles are a subset of equilateral triangles

Equilateral have all three sides the same while isosceles have at least 2 sides the same

Equilateral have all three angles equal while isosceles have at least 2 angles equal

d. bc = 12 and ef = 16

step-by-step explanation:

we are given that δabc : δdef such that .

also, it is given that

so, from the options, we need that .

a.

b.

c.  

d.

as, we can see that only option d gives the same ratio as i.e. .

hence, the possible lengths are bc = 12 and ef = 16.