### Help 1

To solve each case, you need to calculate an *angle*. This angle will have an
arrow pointing to it in the picture.

Usually, you won't be able to work it out straight away. You'll need to calculate some other angles first.

To start your investigation, click on an angle that you think you can calculate straight away, using only the information you already have.

Then work your way towards the 'arrowed' angle.