Question 1210689: In triangle ABC, AB = AC. Compute \angle A in degrees.
Found 2 solutions by ikleyn, KMST:
Answer by ikleyn(54005)   (Show Source):
Answer by KMST(5428)  (Show Source):
You can put this solution on YOUR website! If AB=AC, triangle ABC is an isosceles triangle with base BC and legs (the congruent sides) AB and AC.
The legs are congruent (same length),
and the angles adjacent to the base (B and C) are congruent (same angle measure).
In an isosceles triangle that is not also an equilateral triangle, the angle opposite the base is not congruent to the other two angles and is called the vertical angle.
The information you give us fits an infinite number of isosceles triangles.
I can draw two of them, with different vertical angles, to show what I mean.
For the first triangle, If I knew that the base angles at B and C measured  ,
I would calculate the 
Alternately, I could split the triangle into two congruent right triangles,
and if I knew the length of 2 sides of a right triangle
(  , leg lengths  , or  ),
I could split the triangle into two congruent right triangles,
I could calculate trigonometric ratios,
and from the trigonometric ratios I could calculate all right triangle angles.
More information is needed. What you posted does not give us enough information.
I see a lot of geometry questions that could be answered if we had the figure sketch, or diagram that came with the text. If students could include that figure in some way, their questions are very likely to get answered.
Drawing figures using the tools in this website is not an easy or quick task, but I have been doing it for many years to include pictures in my answers.
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