calculus - What's wrong with my calculation for the area of a circle?

This is my calculation for a simple circle of radius 1. Take a pizza slice of the circle. From geometry, the cone has an area of $r^2\pi * 2\pi / \theta$

Now to get the area of the circle,

$$2\pi^2 \int_0^{2\pi} 1/\theta \, d\theta$$ which yields a nonsensical answer.