Question

Calculate the shaded area. Give your answer to 3 significant figures.

Please include working out, thanks!!

Answer 1

Answer: Only give 3/4 marks

A = π × r²

Area of the whole circle.

Area of a circle = pi*r^2

r = 6.5 cm Note: this is 2 sig digs.

pi= 3.14

Area = 3.14 * 6.5^2

Area = 3.14 * 42.25

Area= 132.665

Area of unshaded smaller circle

pi = 3.14

r = 2.3

Area = 3.14 * 2.3^2

Area = 3.14 * 5.29

Area = 16.61Area of the whole circle.

Area of a circle = pi*r^2

r = 6.5 cm Note: this is 2 sig digs.

pi= 3.14

Area = 3.14 * 6.5^2

Area = 3.14 * 42.25

Area= 132.665

Area of unshaded smaller circle

pi = 3.14

r = 2.3

Area = 3.14 * 2.3^2

Area = 3.14 * 5.29

Area = 16.61

A = 116.113 cm²

Answer 2

`A=A_(big)-A_(small)`

`A=\pi R^2-\pi r^2`

`A=\pi(R^2-r^2)`

`A=\pi(6.5^2-2.3^2)`

`A=\pi(42.25-5.29)`

`A=\pi(36.96)\approx116cm^2`