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Math Help - [SOLVED] Trigonometry help!

  1. #1
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    [SOLVED] Trigonometry help!

    Find the exact value of the other five trigonometric functions of theta:
    (a) sin theta=5/13,and cos theta>0
    (b)cos theta=-4/5,and sin theta >0
    (c)tan theta=15/8,and sec<0
    (d)cot theta=-5/12,and csc theta<0
    (e)csc theta=-2,and cot theta>0

    How to do this questions because i don't understand what i am supposed to do ....
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  2. #2
    A riddle wrapped in an enigma
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    Quote Originally Posted by mj.alawami View Post
    Find the exact value of the other five trigonometric functions of theta:
    (a) sin theta=5/13,and cos theta>0
    (b)cos theta=-4/5,and sin theta >0
    (c)tan theta=15/8,and sec<0
    (d)cot theta=-5/12,and csc theta<0
    (e)csc theta=-2,and cot theta>0

    How to do this questions because i don't understand what i am supposed to do ....
    Hello mj,

    (a) \sin \theta=\frac{5}{13} \ \ \cos \theta>0

    Sine and cosine are both positive in the 1st quadrant, only.

    r^2=x^2+y^2

    \sin=\frac{y}{r}.... \cos=\frac{x}{r}.... \tan=\frac{y}{x}

    \csc=\frac{r}{y}.... \sec=\frac{r}{x}.... \cot=\frac{x}{y}

    From (a), we get y = 5 and r = 13. So 13^2=x^2+5^2
    and eventually get x=12

    Now that we know x = 12, y = 5, r = 13, we can find the other ratios above by substituting these values.
    Last edited by masters; January 14th 2009 at 11:30 AM.
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