Area of a loop from a polar curve

Question

Given the polar curve $$r^2=9\cos(7\theta)$$ I have to evaluate the area of just one loop. What I thought was $$9\cos(7\theta)=0\Leftrightarrow 7\theta=\frac{\pi}{2}\Rightarrow \theta=\frac{\pi}{14}$$ Then, the area of a loop would be $$\int_{-\pi/14}^{\pi/14}\frac{r^{2}}{2}d\theta=\int_{-\pi/14}^{\pi/14}\frac{9\cos(7\theta)}{2}d\theta=\frac{9}{7}$$ I want to know if this is correct.