• # question_answer The stream of a river is flowing with a speed of 2km/h. A swimmer can swim at a speed of 4km/h. What should be the direction of the swimmer with respect to the flow of the river to cross the river straight? [JEE Main 9-4-2019 Morning] A) $60{}^\circ$                       B) $150{}^\circ$C) $90{}^\circ$                       D) $120{}^\circ$

For swimmer to cross the river straight $\Rightarrow 4\sin \theta =2$$\Rightarrow \sin \theta =\frac{1}{2}\Rightarrow \theta ={{30}^{o}}$ So, angle with direction of river flow $=90{}^\circ +\theta =120{}^\circ$ Option [d]