diameter lingkaran 21 cm.luas lingkaran adalah ........cm2

[tex]L=\pi \times {r}^{2} = \frac{22}{7} \times \frac{21}{2} \times \frac{21}{2} = \frac{693}{2} = 346.5[/tex]

l = phi x r x r
l = 22/7 x 10.5 x 10.5
l = 33 x 10.5
l = 346.5 cm^2