1. The problem statement, all variables and given/known data The current in a river flows North at 5mph. A boat starts straight across the river at 8mph relative to the water. (a) What is the speed of the boat relative tot he land? (b) If the river is 2mi wide, how long does it take the boat to cross the river? (c) If the boat sets out straight for the opposite side, how far north will it reach the opposite shore? (d) If we want to have the boat go straight across the river, at what angle should the boat be headed? 3. The attempt at a solution W = 5 Wθ = 90 Wx = 5cos(90) = 0 Wy = 5sin(90) = 5 --- B = 8 Bθ = 0 Bx = 8cos(0) = 8 By = 8sin(0) = 0 ∴ R = √[64+25] = 9.43 Rx = 8 Ry = 5 Rθ = arctan(5/8) = 32 --- (a) 9.43mph --- (b) 60/9.43 = 6.36 ∴ it takes 6.36min for the boat to go 1mi. The actual distance the boat travels is given by the hyp of a triangle across the river, the hyp is given by 2/[cos(32)] = 2.36mi ∴ 2.36*6.36mi = 15m to cross the river --- (c) The distance the boat travels north is give by the opposite side of the triangle across the river, the opp is given by 2.36*sin(32) = 1.25mi North --- (d) I thought about this for a while, and I can't seem to figure it out... The answer the books gives is 38.7° SE Thanks!