The formula of circumference length and area C=2πr
S=(πr 2 )÷2
Semi-circle perimeter and area formula C=πr+2r
S=(πr 2 )÷2
The formula of spherical surface area and volume S=4πr 2
V=(4/3)πr ^3
The above is the formula about circle and ball that I compiled for you. I hope it can help you.