Question

determine a area de um circulo sabendo que a circunferencia desse circulo tem comprimento igual a 15TT cm

Answer 1

Dados:

C = 15π cm
A = ?

Cálculo:

$\displaystyle \mathsf{C = 2\pi r}\\ \displaystyle \mathsf{15\pi = 2\pi r}\\ \\ \displaystyle \mathsf{r = \frac{15\pi}{2\pi}}\\ \\ \displaystyle \mathsf{r = \frac{15}{2}}$

Calculando a área:

$\displaystyle \mathsf{A = \pi r^2}\\ \\ \displaystyle \mathsf{A = \pi (\frac{15}{2})^2}\\ \\ \displaystyle \mathsf{A = \pi . \frac{225}{4}}\\ \\ \displaystyle \mathsf{A = \frac{225 \pi}{4}\: cm^2}$

Resposta: $\displaystyle \mathsf{\frac{225 \pi}{4}\: cm^2}$