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Math Help - Few Trig Questions

  1. #1
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    Few Trig Questions

    I need help with a few questions, if someone could do the problem and show how you did it that would be great.

    Solve In Radians
    2sinx -1 = o

    sinx=squareroot of 3 - sinx

    Angle Addition
    Tan 105 degrees

    Find each value of the trig function
    Sin u = 3/5 cos u = 7/25


    Thanks.
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  2. #2
    A riddle wrapped in an enigma
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    Quote Originally Posted by nyyfn26 View Post
    I need help with a few questions, if someone could do the problem and show how you did it that would be great.

    Solve In Radians
    2sinx -1 = o

    sinx=squareroot of 3 - sinx

    Angle Addition
    Tan 105 degrees

    Find each value of the trig function
    Sin u = 3/5 cos u = 7/25


    Thanks.
    Hi nyyfn26,

    Here's a couple of them.

    [1] 2 \sin x-1=0

    2 \sin x = 1

    \sin x = \frac{1}{2}

    x=\left\{\frac{\pi}{6}, \frac{5\pi}{6}\right\} where  0 \leq x \leq 2 \pi

    [2] \sin x = \sqrt{3}-\sin x

    2 \sin x=\sqrt{3}

    \sin x = \frac{\sqrt{3}}{2}

    x=\left\{\frac{\pi}{3}, \frac{2\pi}{3}\right\} where  0 \le x \le 2 \pi
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  3. #3
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    Quote Originally Posted by masters View Post
    Hi nyyfn26,

    Here's a couple of them.

    [1] 2 \sin x-1=0

    2 \sin x = 1

    \sin x = \frac{1}{2}

    x=\left\{\frac{\pi}{6}, \frac{5\pi}{6}\right\} where  0 \leq x \leq 2 \pi

    [2] \sin x = \sqrt{3}-\sin x

    2 \sin x=\sqrt{3}

    \sin x = \frac{\sqrt{3}}{2}

    x=\left\{\frac{\pi}{3}, \frac{2\pi}{3}\right\} where  0 \le x \le 2 \pi
    Thank you.
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  4. #4
    A riddle wrapped in an enigma
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    And another one,

    [3] \tan 105 = \tan(60+45) = \frac{\tan 60+\tan 45}{1-\tan 60 \tan 45}=\frac{\sqrt{3}+1}{1-\sqrt{3}(1)}
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  5. #5
    A riddle wrapped in an enigma
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    And the last one..... I think you mean to find the other trig ratios given the sine ratio of an angle, and given the cosine of another angle. Is that right?

    [4] \sin u=\frac{3}{5}=\frac{y}{r}

    Use Pythagoras to find x: 5^2=x^2+3^2

    Then, fill in the remaining ratios (could be in QI or QII).

    \tan u=\frac{y}{x} \: \: \: \cot u = \frac{x}{y}

    \cos u=\frac{x}{r} \: \: \: \sec u = \frac{x}{r}

    \sin u=\frac{y}{r} \: \: \: \csc u = \frac{r}{y}

    Do something similar with \cos u = \frac{7}{25}. Could be in QI or QIV.
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  6. #6
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    Thanks a lot man.

    I have one more if you don't mind.

    2sin2x-1=0
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