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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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re(3): Solution - This is how long it took me: | Comment 5 of 13 |
(In reply to re(2): Solution - This is how long it took me: by Eric)

I worked the the problem on Geometer's Sketchpad.
Since the measured angle was 105 degrees exactly
and it easily satisfies the equation
    2 cos(15)         1   
   ----------- = ------------     
      sin(?)      sin(135-?)
I didn't think to write out the derivation.

  Posted by Bractals on 2006-02-25 18:20:55
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