Lesson

Can you work out the value of an angle on a straight line ?

Find the size of the missing angle.

Worked Solution

Idea summary

Angles on a straight line always add up to 180 degrees.

This video shows you how supplementary angles can help us understand that vertically opposite angles are always equal and then how to use vertically opposite angles to answer questions.

Find the size of the missing angle.

Worked Solution

Idea summary

Vertically opposite angles are always equal. 'Vertically opposite' means they are opposite in relation to the vertex, not up and down.

Investigate with and without digital technologies, angles on a straight line, angles at a point and vertically opposite angles. Use results to find unknown angles.