Circles and solids

A sector is a pizza slice. Its area and arc are the same fraction of the whole circle as its angle is of 360.

\frac{arc}{2 π r} = \frac{sector}{π r ^{2}} = \frac{θ}{36 0 ^{\circ}}

Work through it

Fraction. $\frac{1}{4}$

Whole. $36 π$

Result. $9 π$

Center. $(1, - 2)$

Radius. $4$

3-D Pythagorean. $4 + 9 + 36$

Result. $7$

Reading $r = 16$ from the circle equation.

The right side is $r^{2}$ .

The short version
An arc or sector is a fraction of the whole circle: the angle over 360. Volume is base area times height.

Book a free consultation, and we'll help you make a plan.