write an integral that represents the area of the shaded region of the figure. do not evaluate the…

write an integral that represents the area of the shaded region of the figure. do not evaluate the integral.\n$r = 3\\cos(2\\theta)$\n$a=int_{3pi/4}( )d\\theta$

write an integral that represents the area of the shaded region of the figure. do not evaluate the integral.\n$r = 3\\cos(2\\theta)$\n$a=int_{3pi/4}( )d\\theta$

Answer

Explanation:

Step1: Recall area formula in polar coordinates

The area $A$ of a polar - curve $r = f(\theta)$ is given by $A=\frac{1}{2}\int_{\alpha}^{\beta}r^{2}d\theta$.

Step2: Determine the limits of integration

For the polar curve $r = 3\cos(2\theta)$, we want to find the limits of integration for the shaded region. The curve $r = 3\cos(2\theta)$ is a four - leaf rose. To find the limits for the left - hand leaf (the shaded region), we set $r = 0$. So, $3\cos(2\theta)=0$, which gives $2\theta=\pm\frac{\pi}{2}+2k\pi$, or $\theta=\pm\frac{\pi}{4}+k\pi$. For the left - hand leaf, the lower limit $\alpha=\frac{3\pi}{4}$ and the upper limit $\beta=\frac{5\pi}{4}$.

Step3: Substitute $r$ into the area formula

Since $r = 3\cos(2\theta)$, then $r^{2}=9\cos^{2}(2\theta)$. The area integral is $A=\frac{1}{2}\int_{\frac{3\pi}{4}}^{\frac{5\pi}{4}}(9\cos^{2}(2\theta))d\theta$.

Answer:

$\frac{1}{2}\int_{\frac{3\pi}{4}}^{\frac{5\pi}{4}}(9\cos^{2}(2\theta))d\theta$