Finding Missing Angles in Isosceles Triangles

The video tutorial explains how to solve for unknown angles in an isosceles triangle. It begins by introducing the properties of isosceles triangles, emphasizing that two angles are equal. The teacher then demonstrates how to assign a variable to these unknown angles and sets up an equation to solve for the variable. The process involves using the sum of angles in a triangle, subtracting known values, and solving the resulting equation to find the measure of the unknown angles.

What type of triangle is being discussed in the problem?

• Equilateral

• Isosceles

• Scalene

• Right-angled

What is the key property of an isosceles triangle?

• All sides are equal

• Two angles are equal

• All angles are equal

• It has a right angle

If the two equal angles in an isosceles triangle are represented by x, what is the equation for the sum of the angles in the triangle?

• 180° = x + x

• 180° = 40° + x + x

• 180° = 2x

• 180° = 40° + x

What is the sum of all angles in any triangle?

• 270°

• 360°

• 180°

• 90°

What is the first step to isolate x in the equation 180° = 40° + x + x?

• Add 40° to both sides

• Subtract 40° from both sides

• Multiply both sides by 2

• Divide both sides by 2

After subtracting 40° from both sides, what is the resulting equation?

• 140° = x

• 180° = 2x

• 140° = 2x

• 180° = x

What is the value of x in the equation 140° = 2x?

• 70°

• 60°

• 90°

• 80°