180 is angle of the straight line. 44 is subtracted to get angle of only the triangle on the left which is 136. 136 is then divided by 2 since the remaining two angles are equal and you'll get 68. R is part of a right-angled triangle (90°) subtract 68 from that and you will get 22
If you know the radius of a circular track, you can use physics to calculate how fast an object needs to move in order to stay in contact with the track without falling when it reaches the top of the loop.
