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Math Help - Exact Value of trionometric ratio

  1. #1
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    Exact Value of trionometric ratio

    How do i find the exact values without using a calculator? I'll use calculator to check..but how do i do it without...

    tan 5/4 \pi
    and
    sin330^o

    i need help on both please.
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  2. #2
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    sin 330:

    Use the trigonometric identity, sin(360-x) = - sin x
    I can re-write 330 as 360 - 30
    So, sin(360-30) = - sin 30 which is one of the basic ratios to find out.

    tan 5pi/4 = tan (pi+ pi/4)
    Use the identity: tan (pi+ x) = tan x
    so, tan (pi+ pi/4) = tan pi/4.

    That solves the problem.
    Hope it helped,
    MAX
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  3. #3
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    Quote Originally Posted by crosser43 View Post
    How do i find the exact values without using a calculator? I'll use calculator to check..but how do i do it without...

    tan 5/4 \pi
    and
    sin330^o

    i need help on both please.
    you need to learn the unit circle ...

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