1. The problem statement, all variables and given/known data An equilateral triangle of side x is is inscribed in a circle. Express the area of the circle as a function of x. 2. Relevant equations Anything non-trig. I suspect it's got something to do with the Pythagorean theorem. 3. The attempt at a solution I tried getting the radius of the circle by taking ((1/2)x)^2 + y^2 = r^2 My y value was in terms of x. I ended up with an equation that looked nothing like the answer which is supposed to be A(x)=(∏/3)x^2 I what I don't see is how I can get r in terms of x to make any sense.