Properties of Isosceles and Equilateral Triangles

What is the measure of the vertex angle in an isosceles triangle if the base angles are each 72°?

• 108°

• 72°

• 144°

• 36°

What theorem is used to determine that the angles in a triangle add up to 180°?

• Triangle Angle Sum Theorem

• Pythagorean Theorem

• Congruence Theorem

• Similarity Theorem

If the perimeter of an isosceles triangle is 15.2 cm and one of the equal sides is 6.3 cm, what is the length of the base?

• 5.2 cm

• 2.6 cm

• 3.2 cm

• 4.6 cm

If two angles in a triangle are congruent, what type of triangle is it?

• Right

• Equilateral

• Isosceles

• Scalene

Given an isosceles triangle with a vertex angle of 20°, what is the measure of each base angle?

• 70°

• 80°

• 100°

• 90°

How do you calculate the remaining angle in a triangle if you know the other two angles?

• Add the two angles

• Divide the sum of the two angles by 2

• Subtract the sum of the two angles from 180°

• Multiply the two angles

If an equilateral triangle has a perimeter of 7 feet, what is the length of each side?

• 2.33 feet

• 2 feet

• 2.5 feet

• 3 feet

What is the relationship between the angles in an equilateral triangle?

• All angles are 60°

• One angle is 90°

• All angles are 90°

• Two angles are equal

In a bridge profile problem, if the top angle is 158°, what is the measure of each base angle?

• 89°

• 79°

• 22°

• 11°

In the bridge profile problem, why are the base angles equal?

• The triangle is right-angled

• The sides are equal

• The top angle is 158°

• The triangle is scalene