# Chords and radii?

**Geometry**Level 4

Two perpendicular chords of a circle \(A_{1}A_{4}\) and \(A_{2}A_{3}\) intersect at a point \(P\). If for \(i=1, 2, 3\), the length of \(PA_{i}=2^{i}\), the radius of the circle can be expressed as \(\sqrt{a}\) where \(a\) is a positive square-free integer. Find \(a\).