Pls tell how ans is vertical towards east? I've underlined the doubt part...

Pls tell how ans is vertical towards east? I've underlined the doubt part... 4, Itm Example 4.1 Rain is falling vertically With a speed of 35 m Winds starts after sometime with a speed of 12 m s in east to west direction. In which directlon should a boy waiting at a bus stop hold his umbrella ? s Answer "Ihe velocity of the rain and the wind ire represented by the vectors vr and v. in Fig. 17 and are in the direction specified by the )roblem. Using the rule of vector addition, we see that the resultant of v and v is R as shown n the figure. The magnitude of R iS 35 +12 ms- -37 ms the direction 0 that R makes with the vertical iS given by 12 V tan = 0343 Or. nierefore. the boy should hold his umbrella in the vertical plane at an angle of about J W' With the vertical towards the east. 4. rea st q. But to b, Fig• we comp respe