Marie is training for the Marathon. From her home, she runs 5 km south west. She then changes direction and run 3 km N 20 W to get to the park.

a) how far and what direction is the park from Marie's home?

R^2 = 3^2 + 5^2 - 2 x 3x5 cos 65

R^2 = 50.8

R = 7.12

In my textbook the R = 4.6. What am I doing wrong?