a^2+b^2=2c^2
6^2 + 2^2 = 2c^2
36+4 =2c^2
40 = 2c^2
divide by 2
20 =c^2
take the square root of each side
+-sqrt(20) =c
+-sqrt(4) sqrt(5) =c
+- 2 sqrt(5)=c
c= 2 sqrt(5)
- 2 sqrt(5)
