Question

Triangle BDC is an isosceles triangle. Triangle ACE is a right-angled triangle.

Show that triangle ABC is an equilateral triangle.​

Answer 1

Because all sides will be equal to 60 degrees equilateral triangle are all congruent (and therefore they all measure 60° ) however also you can see the other triangles theta and degree and angle which all triangles always add up to 180 degree. So if you got one degree on a triangle 90 then the next one 60 then with out a shadow of doubt the last one will be 30 degrees