Triangle ABC has side AB=AC, and angle BAC = 20 degrees.
D is a point on side AC with AD=BC. Find angle DBC.
Solve this without trigonometry.
(In reply to
Silly guess by Larry)
Larry, there seems to be a fault with this approach... lets analyse
If angle DBC = 60... then angle DBA = 20...
That means Triangle DAB is isoceles...so DA = DB....but DA = BC...so ... DA = DB = BC.... which in turn makes Triangle DBC an isoceles triangle...
But hang on... if DBC is isoceles and angle DBC = 60.... then the triangle is Equilateral...and angle DCB = 60 ( but we know that angle DCB = 80 )
so... back to square 1 !!!
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Posted by Syzygy
on 2004-09-08 08:35:19 |
re: Silly guess
