Answers in terms of π

Answers in terms of π

GCSE(F), GCSE(H),

A more accurate answer, when calculating circle-based objects, can be obtained by not using a value of π, but to leave it as a constant.

Questions may ask for the answer to be given in terms of π. In this instance, do not use a value for π, show the answer instead as a multiple of π.

Examples

1. A circle has a radius of 8 cm. What is the area of the circle? Give your answer in terms of π.

Answer: 64π cm2

Area of a circle ` = pir^2`

`A = pi xx 8^2`

`A = 64pi` cm2 (answer in terms of π)

2. A deep underwater sphere to explore the bottom of the ocean has a diameter of 3m. What is the volume of the sphere? Give your answer in terms of π.

Answer: 4.5π m3

Volume of sphere `= frac(4)(3)pir^3`

`V = frac(4)(3) xx pi xx (frac(3)(2))^3` (change diameter to radius)

`V = 4.5pi` m3