Question

. How are the formulas for the circumference of a circle and area of a circle derived?

Answer 1

they can be derived by using calculus(integration to be precise)


`\pi`
`= (circumference )/(diameter)`(its how pi is defined)
so that gives circumference

to get area , you use integration
`of an elemental ring of radius r and thickness dr and integrate it`
`A= \int\limits^0_r {2 \pi r} \, dr`

that gives the area.

if you don't know calculus yet ,dont worry, just remember the formulae.