Halliday, Resnick & Walker — Equilibrium and Elasticity: Problem 24

24 In Fig. 12-31, a climber with a weight of 533.8 N is held by a belay rope connected to her climbing harness and belay device; the force of the rope on her has a line of action through her center of mass. The indicated angles are $\theta = 38.0^\circ$ and $\phi = 30.0^\circ$. If her feet are on the verge of sliding on the vertical wall, what is the coefficient of static friction between her climbing shoes and the wall?