A famous golfer tees off on a straight 390 yard par 4 and slices his drive to the right. The drive goes 280 yards from the tee. Using a​ 7-iron on his second​ shot, he hits the ball 180 yards and it lands inches from the hole. How many degrees​ (to the nearest​ degree) to the right of the line from the tee to the hole did he slice his​ drive?

2 answers

Instead of the triangle having sides 390, 280, and 180
let's use the similar triangle of 39, 28, 18 , the angles of course remain the same.

looks like we need the angle opposite the side 18,
using the cosine law:
18^2 = 39^2 + 28^2 - 2(39)(28) cosØ
2184cosØ = 1981
cosØ = 1981/2184 = ....

Ø =
Im still not understanding.