# Circle Theorem: Opposite Angles in a Cyclic Quadrilateral Add Up to 180°

(KS3, Year 8)

## How to Use the Circle Theorem where Opposite Angles in a Cyclic Quadrilateral Add Up to 180°

## Question

What is the angle θ in the circle below?## Step-by-Step:

## 1

The opposite angles add up to 180°.

70° + θ = 180°

## 2

Subtract the known angle from 180°.

θ = 180° − 70° = 110°

## Answer:

The angle θ is 110°.## Worksheet

This test is printable and sendable