A circular hole with diameter 6 cm is cut out of a circular piece of card with a diameter of 12 cm.

Question

A circular hole with diameter 6 cm is cut
out of a circular piece of card with a
diameter of 12 cm. The area of the
remaining card, in cm2 , is
(A) 6π
(B) 27π
(C) 36π
(D) 108π

Answer 1

A=(pi)r²

A=(pi)6² (the diameter of the card is 12 cm so the radius is 6 cm)

A=36(pi)

the circular hole has a diameter of 6 cm so it has a radius of 3 cm

A=(pi)r²

A=(pi)3²

A=9(pi)

A=36(pi)-9(pi)

A=27(pi) which is B)