the formula is a^2+b^2=c^2
A and B are the sides doesn't matter which
C is always across from the right angle
so fill x in accordingly
4^2+3^2=x^2
16+9=
25= x^2
square root both 25 and x^2
25 becomes 5
x^2 becomes x
x=5
and just apply this to the other problems
