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Question Number 55561 by otchereabdullai@gmail.com last updated on 26/Feb/19

Commented by otchereabdullai@gmail.com last updated on 26/Feb/19

prof W please am learning this question  solved for me on the 21st but i dont   understand this part : if n=16:α_n =−5<0  and if n=18:α_n =355>180  and how you got the n=17 .   please help me prof W

profWpleaseamlearningthisquestionsolvedformeonthe21stbutidontunderstandthispart:ifn=16:αn=5<0andifn=18:αn=355>180andhowyougotthen=17.pleasehelpmeprofW

Commented by mr W last updated on 27/Feb/19

we have got  α_n =(n−2)×180°−2525°  we want to find how large n is such  that 0<α_n <180°.  if we put (n−2)×180°−2525°=0, we  get n≈16.03. now we try with n=16,  we get α_n =(16−2)×180−2525=−5°,  which is not ok, i.e. n≠16.  then we try with n=17, we get  α_n =(17−2)×180−2525=175°, this is  ok. but is n=17 the only one solution?  let′s try with n=18, and we get  α_n =(18−2)×180−2525=355°, this is  not ok. that means n=17 is the only  one solution.

wehavegotαn=(n2)×180°2525°wewanttofindhowlargenissuchthat0<αn<180°.ifweput(n2)×180°2525°=0,wegetn16.03.nowwetrywithn=16,wegetαn=(162)×1802525=5°,whichisnotok,i.e.n16.thenwetrywithn=17,wegetαn=(172)×1802525=175°,thisisok.butisn=17theonlyonesolution?letstrywithn=18,andwegetαn=(182)×1802525=355°,thisisnotok.thatmeansn=17istheonlyonesolution.

Commented by otchereabdullai@gmail.com last updated on 26/Feb/19

wow! wow! In fact you are an ideal  prof!

wow!wow!Infactyouareanidealprof!

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