Ialways get terribly confused on these, show work?

I'll try my best to explain this.

First off, and equilateral triangle is just a triangle with 3 equal sides.

For the

You just plug in the numbers you're given (m=2 and n=121) So your equation would look like this

Which means the square root of 121. So really the question is simply asking for

Your answer would be 11.

Where are the