Hiya please can you help me understand this question because I keep getting part A wrong and I don't know what I'm doing wrong. If possible please can you do part B as well. Thank you

The diagram shows the penalty area in a football pitch. All measurements are given in yards. O R 10 10 P 18 12 2006 P2 08 The penalty spot is marked at point P. QR is an arc of a circle, centre P, radius 10 yards. The width of the penalty area is 18 yards and the distance of the penalty spot from the goal line is 12 yards, as shown. (a) Calculate the size of angle QPR. (b) Calculate the length of arc QR. 2 Ans (a) 106.30 (b) 18.6 yards