For example, let's say six adjacent angles add up to 360 degrees making them vertical angles, and they can be sorted into three pairs of opposite angles. Two values are known, and four are unknown.

Learn about complementary, supplementary, corresponding, alternate and vertically opposite angles with BBC BItesize Scotland maths for Third Level CfE.

In these pairs of intersecting lines, the opposite angles are equal. They are referred to as vertically opposite angles.