Question

Which best explains why all equilateral triangles are similar?

All equilateral triangles can be mapped onto each other using dilations.
All equilateral triangles can be mapped onto each other using rigid transformations.
All equilateral triangles can be mapped onto each other using combinations of dilations and rigid transformations.
All equilateral triangles are congruent and therefore similar, with side lengths in a 1:1 ratio.

Answer 1

All equilateral triangles are similar because they all have the same angles (each 60°), so one can move and scale any equilateral triangle to match any other. That requires a dilation plus rigid motions, so the correct choice is:

"All equilateral triangles can be mapped onto each other using combinations of dilations and rigid transformations."