How much Guy Wire do I need???

I don't know the proper angle but here is the formula to figure out the length of a guy wire after you determine how far from the base to go. It is common sense the further away the anchor point the better off you'll be. I think!

Example

a= 50'  b=30' c=?

50x50=2500

30x30=900

2500+900=3400

Sq root of 3400=58.3095 feet

ARG!