Knowing a2 + b2 = c2, where a and b are the legs and c is the hypotenuse.
Let a = 6 and c = 8
It does not matter if a or b equals 6 since they are both legs.
62 + b2 = 82
36 + b2 = 64
Get the variable alone to solve for b by adding the opposite to both sides:
b2 = 64 - 36
b2 = 28
Take the square root of both sides: approximately 5.3
Or, find the largest perfect square of 28 which is 4 times 7. Since 7 is not a perfect square and 4 is because 2×2 makes 4, your other possible answer is 2 times the square root of 7.