Question #7f0cc

1 Answer
sente
Oct 13, 2016

x = arctan(-2/7)+pin ~~ 0.2783 + pin

Explanation:

2cos(x)+7sin(x)=0

=> 7sin(x)=-2cos(x)

=> sin(x)/cos(x) = -2/7

=> tan(x) = -2/7

=> x = arctan(-2/7)+pin, n in ZZ

~~0.2783+pin

Note that we add npi to account for tan(x) being periodic with a period of pi, thus tan(arctan(-2/7)) = tan(arctan(-2/7)+pi)=tan(arctan(-2/7)+2pi) = ...

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