If cos x=-1/3 and x is in (90,180), calculate sin x=?

Expert Answers

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cos x = -1/3

We kow that cosx= adjacent/ hypotenuse = -1/3

Then the oppsite = sqrt(3^2 - 1)= sqrt(8) = 2sqrt(2)

Then sinx = opposite/ hypotenuse = 2sqrt2/ 3

Since x is in the second quadrant, the  the sin is positive.

Then sinx = 2sqrt(2)/3 

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