Using a variation of Heron's formula, we can calculate the area of a triangle using only the sides: A = 1/4 √(a2 = b2 + c2)2 - 2(a4 + b4 + c4) Note - everything after the 1/4 is under the radical...
Depends on the type of guitar, and where you get it to be honest.
If you think you'll get bored of playing guitar, get a cheap one (£40-£100) so if you decide to quit, you haven't lost much.
If...