The Pythagorean Theorem is a^2 +b^2 = c^2, where a and b are the sides and c is the hypotenuse ( angled line)
5.
4^2 + 12^2 = c^2
16 + 144 = c^2
160 = c^2
c = √160
c = 4√10
6.
15^2 + b^2 = 27^2
225 + b^2 = 729
b^2 = 729 - 225
b^2 = 504
b = √504
b = 6√14