Since this is a right triangle the angle opposite the side 17 is also 45°
So this can be solved in two ways...
The Law of sines...
x/sin90=17/sin45
x=17/sin45
x≈24.04 to nearest hundredth
or by realizing that both sides are 17 because they are both opposite 45° angles then the hypotenuse x is
x=√(2*17^2)
x=√578
x≈24.04