This is a right triangle, so you can use trigonometric ratios to solve for angle x.
There are three sides to a triangle, and each has a different relationship to angle x.
The hypotenuse is 23. The opposite side is 17. We don't have a value for the adjacent side.
Remember SOH (sin=opp/hyp) CAH (cos=adj/hyp) TOA(tan=opp/adj):
We have values for the opposite side, and the hypotenuse, so we can write:
sin(x) = 17/23
to reverse the sine function, take the arcsine of both sides:
x = arcsin(17/23)
Put this into your calculator (make SURE your mode is degrees, not radians) and round to the nearest whole degree.