If one side of a triangle is 12 and its hypotenuse is 15, what is the length of the other side?

By applying Pythagerean theorom c^2=a^2+b^2.

15^2=12^2+b^2.

b^2 =15^2-12^2.

b^2=225-144.

b^2=81.

b=sqrt(81)

=9 .

The other side  =9.