edit: If I'm understanding correctly you've done using your carried forward error in .
If you do
AZ = AY = 2 - we are told this. We also know angle A is 60 degrees as it's a property of equilateral triangles.
. In this example c = YZ - the side we want to know, a = AZ = 2, b = AY = 2 and C = A = 60 degrees (angle A)
Thus YZ is 2 units across. It has been established that BC = 3 and so the ratio of YZ to BC is 2:3
Similarly the ratio of BC to YZ is the reciprocal which is 3:2
I knew that AZ = 2 and that ZC = 1 therefore 2 + 1 = 3.
At some point I realised that the triangle was an equilateral, and that the angles were 60 degrees, but as I pointed out eariler, the course book does not give enough in the way of examples, and as I pointed out previously I had been told by my tutor that a similar triangle problem that I solved with an answer 21.4cm previously was incorrect and then in the next same example the tutor worked out the same problem with the same answer 21.4cm?
So maybe I was looking at this problem all wrong, and yes I do need more practice to learn this topic.