SOLUTION: How to write a 2 column proof to show that an angle bisector of the vertex of an isosceles triangle is also an altitude.

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Question 388770: How to write a 2 column proof to show that an angle bisector of the vertex of an isosceles triangle is also an altitude.
Answer by richard1234(7193) About Me  (Show Source):
You can put this solution on YOUR website!
I'm not very experienced with writing two-column proofs on this site, or drawing diagrams on this site but I'll give you an outline:

Let the triangle be ABC with angle A = angle C, and BD be the altitude. Since BD is an altitude, then angle ADB = angle CDB = 90 degrees, and since angle A = angle C, angle ABD = angle CBD. By SAS, triangles ABD and CBD are congruent, and then you can show that the altitude is also an angle bisector.