I assume you are learning about right triangle trig.
In this case, h = sin(59) * hypotenuse (have you learned about SOHCAHTOA ?)
But we don't know the hypotenuse. So we need to find it.
105 = cos(59) * hypotenuse (SOHCAHTOA again)
hypotenuse = 105 / cos(59) = 203.8 ft approximately
And then h = sin(59) * 203.8 = 174.7 ft approximately