Question

calcule a area do circulo que tem diametro igual a 20cm.use $\pi$=3,14

Answer 1

R=1/2d
R=1/2.20
R=10cm

A=π.r²
A=3,14.10²
A=3,14.100
A=314cm²

Abraços!

Answer 2

A=\pi r^2\\
\\
A=3,14 10^2\\
\\
A=3,14 * 100
\\
\\
A=314 \ cm^2