Results 1 to 4 of 4
Like Tree1Thanks
  • 1 Post By ebaines

Math Help - Law of Cosines - SAS

  1. #1
    Newbie
    Joined
    Jan 2013
    From
    Phoenix, AZ
    Posts
    13

    Law of Cosines - SAS

    So, I am given SAS.

    Now I must find the remaining angles and side.

    I am given:

    M<A=
    M<B=20 degrees
    M<C=
    a=10mm
    b=
    c=15mm

    and the triangle looks somewhat like this:

    ......10mm
    B\---------|C
    ...\20........|
    ....\...........|
    .....\..........|
    ......\.........|
    .......\........|
    ........\.......|
    15mm.\......|
    ..........\.....|
    ...........\....|
    ............\...|
    .............\..|
    ...............A
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor ebaines's Avatar
    Joined
    Jun 2008
    From
    Illinois
    Posts
    1,096
    Thanks
    317

    Re: Law of Cosines - SAS

    First use the law of cosines to find the length of b. Then use the law of sines to find the angle A, and finally angle C. Post back with what you get for answers and we'k check it for you.
    Thanks from alexthesauceboss
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    Jan 2013
    From
    Phoenix, AZ
    Posts
    13

    Re: Law of Cosines - SAS

    Quote Originally Posted by ebaines View Post
    First use the law of cosines to find the length of b. Then use the law of sines to find the angle A, and finally angle C. Post back with what you get for answers and we'k check it for you.
    Ah! Well, b is ~ 4.85. Then, I did as you said with the law of sines to find that M<A is 44.85 degrees, and M<C is 115.15 degrees.

    Is that correct?
    Follow Math Help Forum on Facebook and Google+

  4. #4
    MHF Contributor ebaines's Avatar
    Joined
    Jun 2008
    From
    Illinois
    Posts
    1,096
    Thanks
    317

    Re: Law of Cosines - SAS

    I get b = 6.56mm. Using the law of cosines:

    b^2 = a^2 + c^2 - 2ac \cos(b) = 10^2 + 15^2 - 2(10)(15)(0.9397) = 43.09 , so b = 6.56
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. sum of cosines
    Posted in the Calculus Forum
    Replies: 1
    Last Post: October 31st 2009, 04:40 PM
  2. Law of Cosines
    Posted in the Trigonometry Forum
    Replies: 1
    Last Post: August 13th 2009, 06:49 AM
  3. sum of cosines
    Posted in the Trigonometry Forum
    Replies: 3
    Last Post: January 14th 2009, 10:02 PM
  4. Law of cosines
    Posted in the Trigonometry Forum
    Replies: 5
    Last Post: February 24th 2008, 01:50 AM
  5. The Law of Cosines
    Posted in the Trigonometry Forum
    Replies: 1
    Last Post: April 28th 2005, 11:29 AM

Search Tags


/mathhelpforum @mathhelpforum