Using the Isosceles triangle theorem to find the measure of x

The video tutorial explains the isosceles triangle theorem, which states that if two sides of a triangle are congruent, then the opposite angles are also congruent. The teacher demonstrates this by identifying congruent angles in a given triangle and solving for the variable x. The process involves setting up an equation based on the sum of angles in a triangle and solving for x. Finally, the teacher calculates the measure of the angles using the value of x.

What does the isosceles triangle theorem state about the angles in an isosceles triangle?

How can you express the angles in terms of x for the isosceles triangle discussed?

What equation is formed to solve for x in the context of the triangle's angles?

What is the value of x after solving the equation?

If x equals 21, what is the measure of the angle in the triangle?