Given:
There are given that the integral:
[tex]\int_{-8}^8\sqrt{64-x^2}dx[/tex]
Explanation:
From the given integral;
[tex]\int_{-8}^8\sqrt{64-x^2}dx[/tex]
Now,
Apply the trigonometry rule that is:
[tex]\int_{-a}^a\sqrt{b-x^2}dx=\int_{-\frac{\pi}{2}}^{\frac{\pi}{2}}bcos^2(u)du[/tex]
Then,
From the function:
[tex]\int_{-8}^8\sqrt{64-x^2}dx=\int_{-\frac{\pi}{2}}^{\frac{\pi}{2}}64cos^2udu[/tex]
Then,
Take the constant out:
So,
[tex]\begin{gathered} \int_{-\frac{\pi}{2}}^{\frac{\pi}{2}}64cos^2udu=64\int_{-\frac{\pi}{2}}^{\frac{\pi}{2}}cos^2udu \\ =64\int_{-\frac{\pi}{2}}^{\frac{\pi}{2}}\frac{1+cos2u}{2}du \\ =\frac{64}{2}\int_{-\frac{\pi}{2}}^{\frac{\pi}{2}}1+cos2udu \end{gathered}[/tex]
Then,
[tex]\begin{gathered} \frac{64}{2}\int_{-\frac{\pi}{2}}^{\frac{\pi}{2}}1+cos2udu=32\int_{-\frac{\pi}{2}}^{\frac{\pi}{2}}1du+\int_{-\frac{\pi}{2}}^{\frac{\pi}{2}}cos2udu \\ =32(\pi+0) \\ =32\pi \end{gathered}[/tex]
Final answer:;
Hence, the correct option is C.