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Angle ABC (Posted on 2006-02-25) Difficulty: 3 of 5
In a triangle ABC, D is the midpoint of BC. Join AD. Angle ADB = 45 degree and angle ACB = 30 degree. Find angle ABC.

No Solution Yet Submitted by akash    
Rating: 2.3000 (10 votes)

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Solution Solution | Comment 1 of 13
 
WOLOG let |BD| = |DC| = 1.
      |AD|        |DC|         1
   --------- = --------- = ---------
    sin(30)     sin(15)     sin(15)
             or
   |AD| = 2 cos(15)
     |AD|         |BD|
   -------- = ------------
    sin(?)     sin(135-?)
            or
    2 cos(15)         1
   ----------- = ------------
      sin(?)      sin(135-?)
            or
    Angle ABC = ? = 105 degrees
 

  Posted by Bractals on 2006-02-25 11:18:25
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