All about circles

$Given \space , \space 2\pi{r} \space =\space \pi r^{2}$

$\Rightarrow \space r \space =\space 2$

$\boxed{\therefore \space 2r \space= \space 4 }$

Area = $\pi$ r $^{ 2 }$

Circumference = $\pi$ d

If they are equal, $\pi$ r $^{ 2 }$ must equal $\pi$ d

This simplifies to r $^{ 2 }$ = d

d=2r, so squaring must equal multiplying by 2.

This gives the radius as 2.

Continuing this, we get 2r = d.

r = 2, so 2 $\times$ 2 = d

d = 4.

πD²/4=πD → D/4=1→ D=4