how to find
limx→π3tan3(x)−3tan(x)cos(x+π6) without L'hopital or taylor/Laurent series
I tried but did not get any answer:
tan2(x)tan(x)−3tan(x)cos(x+π6)=2(sin3(x)−3sin(x)cos2(x))cos3(x)(√3cos(x)−sin(x))=2(sin3(x)−3(sin(x)(1−sin2(x))))cos3(x)(√3cos(x)−sin(x))=21−3(sin(x)−sin2(x))+sin3(x)(1−sin2(x))(cos(x))(√3cos(x)−sin(x))
Answer
limx→π3tan3(x)−3tan(x)cos(x+π6)=
limx→π3tanx(tanx−√3)(tanx+√3)cosxcos(π/6)−sinxsin(π/6)=
limx→π3(2secx)tanx(tanx−√3)(tanx+√3)√3−tanx=−24
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