Two of the angles of triangle ABC are {{q.angles[0]}}° and {{q.angles[1]}}°
Find the size of the external angle at C
That is: the angle between CB and the dotted line
To work this out, you need to know about
However: after you have learnt to do it with these two steps,
try looking for a short cut.
The short cut is spelt out in the algebra version of this problem.