Results 1 to 2 of 2

Math Help - Trigo

  1. #1
    Member maybeline9216's Avatar
    Joined
    Sep 2008
    From
    Singapore~
    Posts
    108

    Trigo

    Please do the last part "Hence state with a brief reason whether angle A+B is acute or obtuse"
    Attached Thumbnails Attached Thumbnails Trigo-b-qn-5.jpg  
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    Joined
    Apr 2005
    Posts
    1,631
    sin(A+B) = 8/15 +[sqrt(5) /5] ------------positive sine value
    So, (A+B) is in the 1st or 2nd quadrants.

    cos(A+B) = 4sqrt(5) /15 -[2/5]
    = 4sqr(5) /15 -[6/15] --------------------positive cosine value
    So, (A+B) is in 1st or 4th quadrants.

    Hence, (A+B) is definitely in the 1st quadrant.
    Therefore, (A+B) is an acute angle.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Trigo Eqn
    Posted in the Trigonometry Forum
    Replies: 7
    Last Post: December 2nd 2009, 03:53 AM
  2. Trigo qn
    Posted in the Trigonometry Forum
    Replies: 4
    Last Post: October 8th 2008, 05:13 AM
  3. Trigo qn
    Posted in the Trigonometry Forum
    Replies: 2
    Last Post: October 7th 2008, 05:39 AM
  4. trigo sum/different~do not do~!
    Posted in the Trigonometry Forum
    Replies: 5
    Last Post: September 11th 2008, 07:43 AM
  5. trigo > i cant do it!
    Posted in the Trigonometry Forum
    Replies: 3
    Last Post: September 9th 2008, 06:43 AM

Search Tags


/mathhelpforum @mathhelpforum