Pie charts help show proportions and percentages between categories, by dividing a circle into proportional segments. Each arc length represents a proportion of each category while the full circle represents the total sum of all the data, equal to 100%.

Pie charts are ideal for giving the reader a quick idea of the proportional distribution of the data.

### Example

Draw a Pie chart with the given angles 50Âº, 70Âº, 140Âº, 100Âº

**Solution:**

Recall that the sum of angles in a circle equal 360Âº, so these angles must add up to 360Âº.

i.e. 50Âº + 70Âº + 140Âº + 100Âº = 360Âº

**First Step:** Draw a circle with centre **O**. Then draw radius **OA**.

**Second Step: **Place your protractor to draw each angle and label the diagrams as shown above.

Place your protractor along **OA** and measure angle **AOB** = 50Âº.

**Third Step: **Place your protractor along **OB** and measure angle BOC = 70Âº

**Fourth Step: **Place your protractor along OC and measure angle COD = 140Âº

**Fifth Step: **Verify that angle **ODA** = 100Âº

### Find the angles of a Pie Chart:

**Example: **

Segun was given N600 in July as pocket money. He spent the money as follows:

Food | N200 |

Transport | N100 |

Books | N120 |

Rent | N150 |

Miscellaneous | N30 |

Total | N600 |

Draw a pie chart to illustrate the data.

**Solution:**

There are 360Âº in a full circle and the total amount spent was N600 is represented by 360Âº.

** âˆ´ ** Express each value as a fraction of the total.

By multiplying the fraction by 360Âº

i.e Food angle for N200 = \( \frac{200}{600} \scriptsize \: \times \: 360^o \\ \scriptsize = 120^o \)

Items | Amount Spent in â‚¦ | Angle |

Food | 200 | \( \frac{200}{600} \scriptsize \: \times \: 360^o \\ \scriptsize = 120^o \) |

Transport | 100 | \( \frac{100}{600} \scriptsize \: \times \: 360^o \\ \scriptsize = 60^o \) |

Books | 120 | \( \frac{120}{600} \scriptsize \: \times \: 360^o \\ \scriptsize = 72^o \) |

Rent | 150 | \( \frac{150}{600}\scriptsize \: \times \: 360^o \\ \scriptsize = 90^o \) |

Miscellaneous | 30 | \( \frac{30}{600}\scriptsize \: \times \: 360^o \\ \scriptsize = 18^o \) |

Total | 600 | 360^{0} |

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