a^2 = c^2 - b^2
b = 6
c = 10
a^2 = 10^2 - 6^2
6^2 = 36
10^2 = 100
a^2 = 100 - 36
100 - 36 = 64
a^2 = 64
8 * 8 = 64
a = 8
