Math problem!

Discussion in 'General Off-Topic Chat' started by MaHe, May 30, 2009.

  1. MaHe

    MaHe one lazy schmo

    Aug 4, 2006
    Need some quick trigonometry help here! [​IMG] 2 * cos 10 / sin 20 equals to 1 / sin 10; But how do you derive one from the another? Thanks!
  2. mcp2

    mcp2 GBAtemp Advanced Fan

    Jun 3, 2007
    UK blud dun kno
    Rearrange to get 1 on it's own and use 1-sin^2 = cos^2, then you have a quadratic equation [​IMG]
  3. FAST6191

    FAST6191 Techromancer

    pip Reporter
    Nov 21, 2005
    United Kingdom
    I will try my usual rule of not giving a direct answer but this case might be hard.

    I assume degrees rather than radians (not that it matters at this stage but I have seen such things end up in calculus territory).

    First stage: rearrange. I went for nothing as a denominator.

    Second stage: trigonometric identities. Rather sly use of one of the more rare identities today, the ones you want are sum formulas for sine and cosine .
    The one in question:
    sin (s + t) = sin s cos t + cos s sin t

    angle is 20 and nicely enough 10 + 10 equals 20 and 10 is the angle of choice in the other factors.

    Hopefully you can see where things go from here.