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1.5: Trigonometry Functions

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    When determining the designate angle we can use different ratios of sides.

    • We can use a ratio of the opposite to the hypotenuse.
    • We can use a ratio of the adjacent to the hypotenuse.
    • We can use a ration of the opposite to the adjacent.

    Each ratio has a trigonometric function that helps turn the ratio into an angle. They are:

    • sin θ = opposite/hypotenuse
    • cos θ = adjacent/hypotenuse
    • tan θ = opposite/adjacent

    One way of remembering the ratios are these mnemonics:

    • SOH – Sine is opposite/ hypotenuse
    • CAH – Cosine is adjacent/hypotenuse
    • TOA – Tangent is opposite/ adjacent

    By the way,

    • sin is short for sine
    • cos is short for cosine
    • tan is short for tangent


    This video walks through how to determine the angle of a right triangle when you have two sides.


    A YouTube element has been excluded from this version of the text. You can view it online here:

    This page titled 1.5: Trigonometry Functions is shared under a CC BY 4.0 license and was authored, remixed, and/or curated by Chad Flinn (BC Campus) via source content that was edited to the style and standards of the LibreTexts platform; a detailed edit history is available upon request.