Tolong jwb pake cara, tentang lingkaran, yg bsa d follow!

Tolong jwb pake cara, tentang lingkaran, yg bsa d follow!

1.
$r = frac{d}{2} = frac{16}{2} = 8 \ d = 16 \ k = pi times d = 3.14 times 16 = 50.24$
2.
$r = 35 \ d = 2 times r = 70 \ k = pi times d = frac{22}{7} times 70 = 220$
3.
$k = 132 \ d = k div pi = 132 div frac{22}{7} \ : : : := 132 times frac{7}{22} = 7 times 6 = 42 \ r = frac{d}{2} = frac{42}{2} = 21$