Question

All ........ triangles are similar . {isosceles, equilateral} I WANT TO KNOW THAT WHY CANNOT THE ANSWER BE ISOSCELES....PLEASE EXPLAIN.

Answer 1

All equilateral triangle are similar.

It cannot be isosceles as for being similar triangle, the corresponding angle must be same and length of sides are in same ratio.
In case of equilateral triangle, angles are always same and sides are in the same ratio, whereas it is not in case of isosceles triangle.

Isosceles triangle means two sides are same.
Taking two isosceles triangle, the angle may not be same, but they are isosceles triangle.

Answer 2

All ___ equilateral ___ triangles are similar............... This is because , all the angles in an equilateral ∆ are of measure = 60° but in an isoceles ∆, corresponding angles vary as there are only two sides equal in an isosceles ∆. Since corresponding angles are not equal in isosceles ∆ , therefore , all isosceles ∆'s are not similar......