trigonometry question? how does 1-cos^2 theta equal sin^2?

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  • 3 years ago

    By the Pythagorean theorem. It is simple geometry

  • 3 years ago

    Since sin^2 (θ) + cos^2(θ) = 1

    1 - cos^2 (θ)

    = sin^2 (θ)

  • Mike G
    Lv 7
    3 years ago

    Right triangle with legs x and y with hypotenuse h

    By Pythagoras

    x^2+y^2 = h^2

    (x/h)^2+(y/h)^2 = 1

    cos^2(θ)+sin2(θ) = 1

    sin^2(θ = 1-cos^2(θ)

  • 3 years ago

    Values for sine and cosine come from the "unit circle" or a circle with radius = 1. The sine and cosine values are the projections of that radius on the vertical (sine) and horizontal (cosine) axis for angles 0 - 360°. In other words a right triangle with hypotenuse = 1.

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  • phuong
    Lv 5
    3 years ago

    From the equation : sin^2 ( theta ) + cos ^2( theta ) = 1

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