Results 1 to 3 of 3

Math Help - Solving Trig problems

  1. #1
    Junior Member
    Joined
    Jul 2008
    Posts
    46

    Solving Trig problems

    Okay so i have two problems that I cant solve completely.
    One is a a word problem
    1. A sharpshooter intends to hit a target at a distance of 1000 yards with a rifle having a muzzle velocity of vo=1200 feet per second. Neglecting air resistance, determine the gun's minimum angle of elevation x if the range r is given by
    r=(1/32)vo^2(sin(2x))
    I can solve this problem down to 1/15 = sin(2x) (assuming i did this much right).
    My second problem is:
    Solve tan(x+pi)+2sin(x+pi)=0 i started to solve this using the sum and difference formulas.
    If anyone could help that would be great. Thanks
    AC
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Rhymes with Orange Chris L T521's Avatar
    Joined
    May 2008
    From
    Chicago, IL
    Posts
    2,844
    Thanks
    3
    Quote Originally Posted by Casas4 View Post
    Okay so i have two problems that I cant solve completely.

    My second problem is:
    Solve tan(x+pi)+2sin(x+pi)=0 i started to solve this using the sum and difference formulas.
    If anyone could help that would be great. Thanks
    AC
    \tan(x+\pi)+2\sin(x+\pi)=0

    \implies \frac{\sin(x+\pi)}{\cos(x+\pi)}+2\sin(x+\pi)=0

    \implies \sin(x+\pi)\bigg[\frac{1}{\cos(x+\pi)}+2\bigg]=0

    We can get 2 equations out of this:

    \sin(x+\pi)=0 and \cos(x+\pi)=-\tfrac{1}{2}

    Can you take it from here? You don't need to apply the sum and difference formulas here.

    --Chris
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Senior Member
    Joined
    Dec 2007
    From
    Melbourne
    Posts
    428
    I can solve this problem down to 1/15 = sin(2x) (assuming i did this much right).
    The next step is, depending on the notation you use,
    2x = \arcsin(\frac{1}{15})
    or
    2x = \sin^{-1}(\frac{1}{15})
    You then solve for x normally by dividing both sides by 2.

    What the notation actually means is inverse sin, so if y = sin(x) then x = arcsin(y).

    Often you will be expected to answer in turns of arcsin, but if you have a calculator you can turn it into a decimal approximation. the button on the calculator will probably be labelled \sin^{-1} or asin.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Trig word problem - solving a trig equation.
    Posted in the Trigonometry Forum
    Replies: 6
    Last Post: March 14th 2011, 08:07 AM
  2. Replies: 7
    Last Post: April 15th 2010, 09:12 PM
  3. Some more problems..(solving for x)
    Posted in the Pre-Calculus Forum
    Replies: 3
    Last Post: September 20th 2009, 03:17 PM
  4. Solving Trig problems using similar Triangles
    Posted in the Trigonometry Forum
    Replies: 7
    Last Post: March 26th 2009, 07:38 PM
  5. Solving problems
    Posted in the Math Topics Forum
    Replies: 1
    Last Post: March 13th 2009, 03:35 AM

Search Tags


/mathhelpforum @mathhelpforum