This worksheet focuses on using the sum of angles in a triangle to find missing angles. It assumes that students are already familiar with angles on a straight line, vertically opposite angles, and angles in parallel lines.
The first section covers all the different types of triangles and their properties. There is a short exercise where students practise choosing the correct type(s) of triangle based on the information given.
The second section begins with the result for the sum of angles in a triangle, including a proof using angles on a straight line. There are then some examples of finding angles - these are to be completed with your class. The exercise that follows is for students to attempt themselves.
Answers to both exercises are included.