word problem

Question

sally can jog 8mph along paved road, but only 3mph in the sand on the beach. Because of a river between houses, it is necessary to jog in the sand to the rodd, continue in the road, and then jog directly back in the sand to get from one house to another. the time T to get from one house to the other as a function of the angle∅=

T(∅)=1+2/3sin∅ - 1/4tan∅ for 0degrees<∅<90degrees

 

Calculate the time T for ∅=30 degrees-how long is sally on paved road?, 45 degrees? 60 degrees? 90 degrees?

describe the path taken, why can't the formula for T be used in this case?

 

Answer 1

I do not understand the angle, when it varies, the variation depends on what? I feel that the formula is missing some constraints or explanations as for example, the angle is of the surface? of the soil?