Why..................?? Per the P theorem.........if I know that the hyp is one.......which it is...........and one side is 1/2................0.5..................then a squared + b squared = C squared..........C being the hyp......which is one...................................I will call b..........the length of the left side.....and A the side along the X axis............0.5..........................so it would be (0.5)squared + b squared = 1 squared..................................0.5 squared is 0.25................+ b squared........= 1 squared, which is still one.....................................so........0.25 + b squared = 1...............subtract 0.25 from both sides............algebra....................u are left with............b squared = 0.75.............1 - 0.25 = 0.75........................b squared = 0.75............just take the square root of 0.75.......which is 0.866.................................