Results 1 to 7 of 7
Like Tree1Thanks
  • 1 Post By Chris L T521

Math Help - Easy enough but apparently my math tutor doesnt understand that I DONT GET IT.

  1. #1
    Junior Member
    Joined
    Sep 2009
    Posts
    27

    Easy enough but apparently my math tutor doesnt understand that I DONT GET IT.

    Alright so ive been talking to my math tutor from the univ. about this single question for about a week now and i HAVE to get it done.

    If Tan\alpha = {- 7\over24} and Cot\beta = {3\over4}

    For a second quadrant angle \alpha and a third quadrant angle \beta

    Have to find

    Sin(\alpha + \beta) , Cos (\alpha + \beta) , Tan (\alpha + \beta), Sin(\alpha - \beta) , Cos(\alpha - \beta) , Tan(\alpha - \beta)
    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 Djaevel View Post
    Alright so ive been talking to my math tutor from the univ. about this single question for about a week now and i HAVE to get it done.

    If Tan\alpha = {- 7\over24} and Cot\beta = {3\over4}

    For a second quadrant angle \alpha and a third quadrant angle \beta

    Have to find

    Sin(\alpha + \beta) , Cos (\alpha + \beta) , Tan (\alpha + \beta), Sin(\alpha - \beta) , Cos(\alpha - \beta) , Tan(\alpha - \beta)
    Construct one triangle that refers to \alpha and one that refers to \beta.

    Since \alpha is in quadrant II, we let the side opposite the angle have length 7 and the side adjacent to the angle have length -24

    So that means that the hypotenuse of our triangle will have length \sqrt{(-24)^2+7^2}=25

    Therefore, we can conclude that \sin \alpha =\frac{7}{25} and \cos\alpha = \frac{-24}{25}.

    Does this make sense so far?

    You should do something similar for \beta.

    Then once you have a right triangle, it is easy to find \sin\beta, \cos\beta and the like.

    If this doesn't make sense, post back. To help it sink in, try to draw the triangle I described to you above.
    Thanks from topsquark
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Junior Member
    Joined
    Sep 2009
    Posts
    27
    Ohhh i was like trying to use.. well nevermind lol dont know what i was doing/thinking >< thanks haha
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Junior Member
    Joined
    Sep 2009
    Posts
    27
    So for the \beta triangle it would be like x=-3 and y=-4 ? then get hyp and go from there?
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Rhymes with Orange Chris L T521's Avatar
    Joined
    May 2008
    From
    Chicago, IL
    Posts
    2,844
    Thanks
    3
    Quote Originally Posted by Djaevel View Post
    So for the \beta triangle it would be like x=-3 and y=-4 ? then get hyp and go from there?
    Follow Math Help Forum on Facebook and Google+

  6. #6
    Newbie
    Joined
    Mar 2013
    From
    Iowa City, IA
    Posts
    13

    Re: Easy enough but apparently my math tutor doesnt understand that I DONT GET IT.

    Follow Math Help Forum on Facebook and Google+

  7. #7
    Super Member
    Joined
    Jul 2012
    From
    INDIA
    Posts
    829
    Thanks
    209

    Re: Easy enough but apparently my math tutor doesnt understand that I DONT GET IT.

    My suggestion would be at first stage forget the sign, just find the trig values. e.g., tan A = 7/24 we know that the hypotenuse will be 25. so we will get sin A = 7/25; cosA = 23/25, tan A = 7/24; cot A = 24/7, sec A = 24/25 and csec A = 25/7.
    Now in second step see where that angle lies, in this case A lies in II quadrant, we know that in second quadrant sine and its reciprocal csec are positive and all rest are negative. Put signs accordingly and you have the result:
    sin A = 7/25; cosA = - 23/25, tan A = - 7/24; cot A = - 24/7, sec A = - 24/25 and csec A = 25/7.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. I dont understand this triangle math question
    Posted in the Geometry Forum
    Replies: 3
    Last Post: April 5th 2009, 11:11 AM
  2. Function question (easy but i dont understand)
    Posted in the Math Topics Forum
    Replies: 3
    Last Post: January 30th 2009, 09:00 PM
  3. What I dont understand is
    Posted in the Calculus Forum
    Replies: 2
    Last Post: March 31st 2008, 06:57 PM
  4. Replies: 4
    Last Post: March 16th 2008, 02:37 AM
  5. I dont understand this..
    Posted in the Trigonometry Forum
    Replies: 1
    Last Post: August 18th 2007, 04:48 PM

Search Tags


/mathhelpforum @mathhelpforum