Results 1 to 3 of 3

Math Help - Quadrilateral

  1. #1
    Member
    Joined
    Apr 2009
    From
    california
    Posts
    121

    Quadrilateral

    Quadrilateral ABCD has AB = BC = CD. Angle ABC = 70 degrees and Angle BCD = 170 degrees. What is the degree measure of angle BAD?


    Could I just get some hints please?

    Vicky.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    Joined
    Dec 2007
    From
    Ottawa, Canada
    Posts
    3,162
    Thanks
    70
    Let AB = BC = CD = 1

    Use Sine Law and isosceles triangle BCD to calculate BD (you should get ~1.992)

    Do you see that angle ABD = 65 (70 - 5) ?
    Use Cosine Law and triangle ABD to calculate AD (you should get ~1.813)

    We now have BD / sin(A) = AD / sin(65)
    From that, calculate angle A (you should get 85 degrees.

    If you draw a diagram, it'll be easier for you to follow above steps.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Member
    Joined
    Apr 2009
    From
    california
    Posts
    121
    Quote Originally Posted by Wilmer View Post
    Let AB = BC = CD = 1

    Use Sine Law and isosceles triangle BCD to calculate BD (you should get ~1.992)

    Do you see that angle ABD = 65 (70 - 5) ?
    Use Cosine Law and triangle ABD to calculate AD (you should get ~1.813)

    We now have BD / sin(A) = AD / sin(65)
    From that, calculate angle A (you should get 85 degrees.

    If you draw a diagram, it'll be easier for you to follow above steps.
    Thanks for your help.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Quadrilateral
    Posted in the Algebra Forum
    Replies: 1
    Last Post: June 25th 2010, 11:31 PM
  2. quadrilateral
    Posted in the Geometry Forum
    Replies: 0
    Last Post: June 9th 2010, 06:39 PM
  3. Quadrilateral
    Posted in the Geometry Forum
    Replies: 2
    Last Post: April 8th 2010, 11:24 AM
  4. quadrilateral help!!
    Posted in the Geometry Forum
    Replies: 1
    Last Post: April 26th 2009, 01:08 PM
  5. please help, quadrilateral
    Posted in the Geometry Forum
    Replies: 3
    Last Post: April 18th 2009, 08:52 AM

Search Tags


/mathhelpforum @mathhelpforum