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Measure that angle IV (Posted on 2004-11-02) Difficulty: 4 of 5
Triangle ABC is isosceles with AB=AC. Point D is on side AB such that angle BCD is 70 degrees. Point E is on side AC such that angle EBC is 60 degrees. Angle ABE equals 20 degrees, and angle DCE equals 10 degrees.

Find angle EDC. Justify your answer.

See The Solution Submitted by Brian Smith    
Rating: 3.6667 (9 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
re(2): Not sure why I don't get the same answer | Comment 19 of 21 |
(In reply to re: Not sure why I don't get the same answer by Charlie)

Yes, Sorry, well spotted - I meant DG!  I noticed a problem with my solution (as DG is not equal to HE). Never mind  as HE = DG+FH and FH/y = cos 80, so.....

tan DEH = [sin80*(sin70/sin30 - sin60/sin40)]/[(sin80/sin20)(sin80/sin20-sin70/sin30) + cos80*(sin70/sin30-sin60/sin40)]

DEH = 39.24 degrees

and EDC = 30.76 degrees.

 

 

 

Edited on November 11, 2004, 9:44 am
  Posted by Jils on 2004-11-11 08:43:30

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