Geometry

Question Analysis:
This question involves the properties of isosceles triangles and the sum of interior angles of a triangle.
The main focus is on using the fact that in an isosceles triangle, the base angles are equal and then applying the angle - sum property of a triangle.

Key Concept Explanation:
In an isosceles triangle, if two sides are equal, the angles opposite those sides (base angles) are equal.
The sum of the interior angles of any triangle is .

Step - by - Step Solution:
Since the triangle is isosceles and one of the base angles is , the other base angle is also .
Let the vertex angle be .
Using the angle - sum property of a triangle: .
First, add the base angles:

Click "Show Answer" to reveal the answer and analysis