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Kayla
Kayla asked in Science & MathematicsMathematics · 6 years ago

Find cos Θ if sin=2/3 Assume the terminal side of the angle falls in Quadrant 2.  Show all work.?

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  • ?
    Lv 7
    6 years ago

    since cos^2 x + sin^2 x = 1

    or cos^2 x = 1 - sin^2 x = 1 - (2/3)^2 = 1 - 4/9 = 5/9

    cos x =+- sqrt(5/9)

    and since x is in 2 quad we choose the -ve sing

    so cos x = - sqrt(5) / 3

  • ?
    Lv 7
    6 years ago

    Opp/hyp = 2/3

    Adj = √(3² - 2²) = √(5)

    cosθ = -√(5)/3. Negative since θ in QII

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