You would need to use the equation a^2 + b^2 = c^2
The legs would go in for a and b, with the hypotenuse being c.
Plugging in would give you,
12^2 + 35^2 = c^2
Now you want to apply the 2 square.
144 + 1225 = c^2
Now add.
1369 = c^2
Now put 1369 under a squareroot sign since you want to apply the 2 square to both sides.
[tex]\sqrt{1369}[/tex] = c
Now do the square root sign.
37 = c