Question 796·Medium·Math

A central angle has its corner at the circle’s center. A full turn is $360^\circ$, so the $135^\circ$ sector covers this fraction of the circle:

The $8$ is the radius, so put it into the circle-area formula:

Type $8^2$ in Desmos. It prints $64$, so the whole circle’s area is $64\pi$ square units.

The sector covers $\frac{3}{8}$ of the circle, so take $\frac{3}{8}$ of its area:

Don’t use the circumference $2\pi r$ here. That measures distance around the circle, not area inside it.

To keep $\pi$ exact, type $\frac{3}{8}\cdot64$ in Desmos. It prints $24$, the number multiplying $\pi$. The sector’s area is $24\pi$ square units. Choice B.