A 67 kg bike racer climbs a 1250 m-long section of road that has a slope of 4.3 

By how much does his gravitational potential energy change during this climb?

Since the biker starts on level ground, initial PE=0J
The angle(θ) and hypotenuse length(h) given, we can calculate height.

ΔU=mgh

First is to find the height. The angle is given and also the length is given.

sin(4.3) x 1250 = 93.73 m

67 x 9.8 x 93.73 = 61538 J