Thanks that really helps with the first question. I still don't understand how you're calculating for the second question though..

I worked out EG before AG, because you need it first. EG is 10, because of the triad 6,8,10. Then you use 10 from EG and 2 from EA to find AG.

2^2+10^2=AG^2

4+100=AG^2

So root of 104 = AG

That is root of 4 x root of 26, which simplifies to 2x root of 26

Hopefully that made sense

.