May given ka ng circumference or area, substitute mo yung mga values nila, yung pi ay automatically 3.14. Pagkatapos, divide mo ung 3.14, sa total area or circumference, pag area, isquare root mo yung total area, pag circumference, divide both sides by 2.
Ex.
Given:
π
A=9π
radius=?
A=πr²
9π=πr²
Divide both sides by π
9=r²
√9=r
r=3
Hope this helps =)
