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`.
A circle has a radius of 8 cm. What is the area of the circle?
Give your answer in terms of `π`.
| Area of a circle: | A | ` = pir^2` |
| Substitute: | A | ` = pi xx 8^2` |
| In terms of `pi`: | A | ` = 64pi` |
Answer: 64`π` cm2
A surface radar is sweeping an arc of 60º; with a range of 12km. What is the surface area being swept by the radar?
Give your answer in terms of `π`.
Area of a circle is given by A = `π`r2.
Area of whole circle = `π` x 122 = 144`π`
But the radar is sweeping 60/360º of a whole circle,
| Area being swept: | A | = 144`π` x `frac(60)(360)` |
| = 144`π` ÷ 6 | ||
| In terms of `pi`: | = 24`pi` |
Answer: 24`π` km2