I'm new to the forum and i'm not even sure that this question should be posted in this section but i hope someone can point me in the right direction.

A piece of string 30 inches long has its two ends joined together and is stretched by three pegs so as to form a triangle.

What is the largest triangular area that can be enclosed by the string?

I think I need to express the Area of the triangle in terms of the length of string (which is my problem) then differentiate and equate to zero to find the maxima.

Help appreciated.