# find the value of cosine function tan θ = -2/3 and angle θ lies in the second quadrant, what is the value of cos θ

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hala718 | Certified Educator

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tan x = -2/3

We need to find cosx such that x is in the second quadrant.

We know that:

sinx/cosx = tanx = -2/3

==> sinx =...

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## Related Questions

giorgiana1976 | Student

Since the angle θ is in the second quadrant, then the value of the cosine function is negative.

(cos θ)^2 = 1/[1 + (tan θ)^2]

cos θ = 1/sqrt[1 + (tan θ)^2]

tan θ = -2/3 => (tan θ)^2 = 4/9

cos θ = 1/sqrt(1 + 4/9)

cos θ = 3/sqrt13

cos θ = 3*sqrt13/13

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