# Limit of triangle in a circle

**Calculus**Level 5

\(\triangle ABC\) is an isosceles triangle inscribed in a circle of radius \(10\). If \(AB=AC\), then evaluate \(\displaystyle \lim_{h \to 0} \frac {\phi}{P^{3}}\), where \(h\) is altitude from point \(A\) to \(BC\), \(\phi\) is area of triangle and \(P\) is perimeter of triangle. If the answer is \(\dfrac {X}{Y}\), then find the value of \(XY\)