Using the law of sines, sin80°/3.1 = sin∠QSR/2.4 ∠QSR = sin^-1(2.4sin80°/3.1) ≈ 49.679° ∠SQR = 180° - 80° - 49.679° (angles in a triangle) = 50.321° sin50.321°/RS = sin80°/3.1 RS = (3.1sin50.321°/sin80°) = 2.4 units (nearest tenth) The length of line RS is 2.4 units.
Let s be the speed of the boat in still water. Let c be the speed of the current. s - c = 48/6 = 8 s + c = 48/4 = 12 Adding the two equations, we get: 2s = 20 s = 10 The answer is 10 miles per hour.
