In order to find the value of x, use the sine of 18°, and consider that x is the hypotenuse and the side with length 17 is the opposite side to 18°. Then, you have:
sin 18° = oppsite side/hypotenuse
sin 18° = 17/x
solve the previous equation for x, as follow:
x = 17/(sin 18°)
x = 55.01
Hence, the value of x is 55.01
