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Question Number 16489 by Tinkutara last updated on 23/Jun/17
Rain is falling vertically with a speed  of 4 m/s. After some time, wind starts  blowing with a speed of 3 m/s in the  north to south direction. In order to  protect himself from rain, a man  standing on the ground should hold his  umbrella at an angle θ given by  (1) θ = tan^(−1) 3/4 with the vertical  towards south  (2) θ = tan^(−1) 3/4 with the vertical  towards north  (3) θ = cot^(−1) 3/4 with the vertical  towards south  (1) θ = cot^(−1) 3/4 with the vertical  towards north
$$\mathrm{Rain}\:\mathrm{is}\:\mathrm{falling}\:\mathrm{vertically}\:\mathrm{with}\:\mathrm{a}\:\mathrm{speed} \\ $$$$\mathrm{of}\:\mathrm{4}\:\mathrm{m}/\mathrm{s}.\:\mathrm{After}\:\mathrm{some}\:\mathrm{time},\:\mathrm{wind}\:\mathrm{starts} \\ $$$$\mathrm{blowing}\:\mathrm{with}\:\mathrm{a}\:\mathrm{speed}\:\mathrm{of}\:\mathrm{3}\:\mathrm{m}/\mathrm{s}\:\mathrm{in}\:\mathrm{the} \\ $$$$\mathrm{north}\:\mathrm{to}\:\mathrm{south}\:\mathrm{direction}.\:\mathrm{In}\:\mathrm{order}\:\mathrm{to} \\ $$$$\mathrm{protect}\:\mathrm{himself}\:\mathrm{from}\:\mathrm{rain},\:\mathrm{a}\:\mathrm{man} \\ $$$$\mathrm{standing}\:\mathrm{on}\:\mathrm{the}\:\mathrm{ground}\:\mathrm{should}\:\mathrm{hold}\:\mathrm{his} \\ $$$$\mathrm{umbrella}\:\mathrm{at}\:\mathrm{an}\:\mathrm{angle}\:\theta\:\mathrm{given}\:\mathrm{by} \\ $$$$\left(\mathrm{1}\right)\:\theta\:=\:\mathrm{tan}^{−\mathrm{1}} \mathrm{3}/\mathrm{4}\:\mathrm{with}\:\mathrm{the}\:\mathrm{vertical} \\ $$$$\mathrm{towards}\:\mathrm{south} \\ $$$$\left(\mathrm{2}\right)\:\theta\:=\:\mathrm{tan}^{−\mathrm{1}} \mathrm{3}/\mathrm{4}\:\mathrm{with}\:\mathrm{the}\:\mathrm{vertical} \\ $$$$\mathrm{towards}\:\mathrm{north} \\ $$$$\left(\mathrm{3}\right)\:\theta\:=\:\mathrm{cot}^{−\mathrm{1}} \mathrm{3}/\mathrm{4}\:\mathrm{with}\:\mathrm{the}\:\mathrm{vertical} \\ $$$$\mathrm{towards}\:\mathrm{south} \\ $$$$\left(\mathrm{1}\right)\:\theta\:=\:\mathrm{cot}^{−\mathrm{1}} \mathrm{3}/\mathrm{4}\:\mathrm{with}\:\mathrm{the}\:\mathrm{vertical} \\ $$$$\mathrm{towards}\:\mathrm{north} \\ $$
Answered by ajfour last updated on 23/Jun/17
Commented by chux last updated on 23/Jun/17
good morning Mr Ajfour. please  can you send a screenshot of how  you use this app in drawing and   writing. I ve tried it but I didnt  really get it. Thanks in advance.
$$\mathrm{good}\:\mathrm{morning}\:\mathrm{Mr}\:\mathrm{Ajfour}.\:\mathrm{please} \\ $$$$\mathrm{can}\:\mathrm{you}\:\mathrm{send}\:\mathrm{a}\:\mathrm{screenshot}\:\mathrm{of}\:\mathrm{how} \\ $$$$\mathrm{you}\:\mathrm{use}\:\mathrm{this}\:\mathrm{app}\:\mathrm{in}\:\mathrm{drawing}\:\mathrm{and}\: \\ $$$$\mathrm{writing}.\:\mathrm{I}\:\mathrm{ve}\:\mathrm{tried}\:\mathrm{it}\:\mathrm{but}\:\mathrm{I}\:\mathrm{didnt} \\ $$$$\mathrm{really}\:\mathrm{get}\:\mathrm{it}.\:\mathrm{Thanks}\:\mathrm{in}\:\mathrm{advance}. \\ $$
Commented by ajfour last updated on 23/Jun/17
i have an old device, dont have  this screenshot feature..  its just that i got friendlier with  this app (Lekh Diagram) with use.
$${i}\:{have}\:{an}\:{old}\:{device},\:{dont}\:{have} \\ $$$${this}\:{screenshot}\:{feature}.. \\ $$$${its}\:{just}\:{that}\:{i}\:{got}\:{friendlier}\:{with} \\ $$$${this}\:{app}\:\left({Lekh}\:{Diagram}\right)\:{with}\:{use}. \\ $$
Commented by Tinkutara last updated on 23/Jun/17
Thanks Sir!
$$\mathrm{Thanks}\:\mathrm{Sir}! \\ $$

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