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` cm^{2}

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`r^{2}.

Area of whole circle = `π` x 12^{2} = 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` km^{2}

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