Solve the problem.
When granular materials are allowed to fall freely, they form conical (cone-shaped) piles. The naturally occurring angle of slope, measured from the horizontal, at which the loose material comes to rest is called the angle of repose and varies for different materials. The angle of repose θ is related to the height h and base radius r of the conical pile by the equation θ = cot^-1(r/h). Find the angle of repose for a granular material which forms a cone-shaped pile with a height of 13 feet and a base diameter of 27.3 feet.

Question

Solve the problem.
When granular materials are allowed to fall freely, they form conical (cone-shaped) piles. The naturally occurring angle of slope, measured from the horizontal, at which the loose material comes to rest is called the angle of repose and varies for different materials. The angle of repose θ is related to the height h and base radius r of the conical pile by the equation θ = cot^-1(r/h). Find the angle of repose for a granular material which forms a cone-shaped pile with a height of 13 feet and a base diameter of 27.3 feet.