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  1. #1
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    trig help

    In my work they are asking for the exact values of \frac{\Pi}{8} in all forms: Sin, Cos, Tan and recipricols by using double angle formula's. Sin and Cos of \frac{\Pi}{8} make sense but i have a query involving Tan and Cotan.

    i have figured out that sin\frac{\Pi}{8} = \frac{-\sqrt2+2}{2}

    i have also figured out that cos\frac{\Pi}{8} = \frac{\sqrt2+2}{2}

    How would i go about figuring out Tan\frac{\Pi}{8}, Using the respective double angle formula didn't work so now i am stumped. Also i don't know at which point i should switch the numerator and denominator for Recipricol functions

    Cosec(\frac{\Pi}{8}) = \frac{1}{Sin\frac{\Pi}{8}}

    = \frac{1}{\frac{-\sqrt2+2}{2}} = \frac{2}{-\sqrt2+2} and times by the conjugate to get the answer?

    any help would greatly boost my confidence
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  2. #2
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    Quote Originally Posted by SirNostalgic View Post
    In my work they are asking for the exact values of \frac{\Pi}{8} in all forms: Sin, Cos, Tan and recipricols by using double angle formula's. Sin and Cos of \frac{\Pi}{8} make sense but i have a query involving Tan and Cotan.

    i have figured out that sin\frac{\Pi}{8} = \frac{-\sqrt2+2}{2}

    i have also figured out that cos\frac{\Pi}{8} = \frac{\sqrt2+2}{2}

    How would i go about figuring out Tan\frac{\Pi}{8}, Using the respective double angle formula didn't work so now i am stumped. Also i don't know at which point i should switch the numerator and denominator for Recipricol functions

    Cosec(\frac{\Pi}{8}) = \frac{1}{Sin\frac{\Pi}{8}}

    = \frac{1}{\frac{-\sqrt2+2}{2}} = \frac{2}{-\sqrt2+2} and times by the conjugate to get the answer?

    any help would greatly boost my confidence
    The sine one is done here. But you only need to get one of sine or cos using the double angle formula - all the others can be got using the Pythagorean Identity.
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  3. #3
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    so since Sin = O/H i should put those values on a triangle and use pythagoras to figure out the adjacent?

    and this should give me the values of the rest?
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