Question

what is the length of sides in inches of an equilateral triangle having an included cirle of 60 inches

Answer 1

I assume 60 is the circumference of the circle.
if you sketch the graph, you will see that the radius from the center to the base, half the base, and the line segment form the center to one of the bottom vertex form a 30-60-90 degree triangle, the shortest leg is the radius of the circle, r.
the longer leg is √3r, and the hypotenuse is 2r.
the base of the triangle is 2√3r. 
find r: 2πr=60, r=60/2π
2√3r=2√3*60/(2π)=60√3/π=33