Question

determine a área de um círculo sabendo que a circunferência desse círculo tem o comprimento igual a 15​

Answer 1

$\large\boxed{\begin{array}{l}\rm c=2\cdot\pi\cdot r\\\rm 15=2\cdot\pi\cdot r\\\rm r=\dfrac{15}{2\pi}\\\\\rm A=\pi\cdot r^2\\\\\rm A=\pi\cdot\bigg(\dfrac{15}{2\pi}\bigg)^2\\\\\rm A=\backslash\!\!\!\pi\cdot\dfrac{225}{4\diagup\!\!\!\!\!\pi^2}\\\\\rm A=\dfrac{225}{4\pi}\end{array}}$