Understanding Equilateral and Isosceles Triangles

What is the name of the angle formed where the two legs of an isosceles triangle meet?

• Vertex angle

• Base angle

• Right angle

• Supplementary angle

According to the Base Angle Theorem, if two sides of a triangle are congruent, what can be said about the angles opposite these sides?

• They are right angles

• They are supplementary

• They are congruent

• They are complementary

What does the converse of the Base Angle Theorem state about a triangle with two congruent angles?

• The triangle is equilateral

• The sides opposite these angles are congruent

• The triangle is right-angled

• The triangle is scalene

If a triangle is equilateral, what can be said about its angles?

• All angles are 90 degrees

• All angles are 45 degrees

• All angles are 60 degrees

• All angles are 30 degrees

In an isosceles triangle, if the base angles are equal, what can be inferred about the sides?

• The sides are perpendicular

• The sides are parallel

• The sides opposite the base angles are congruent

• The sides are unequal

If an equilateral triangle has a side length of 4, what is the value of y if y represents the side length?

• 2

• 3

• 4

• 5

In a triangle where all angles are equal, what is the measure of each angle?

• 60 degrees

• 120 degrees

• 90 degrees

• 45 degrees

How can you prove that two triangles are congruent using the Side-Angle-Side (SAS) postulate?

• By showing all three angles are equal

• By showing all three sides are equal

• By showing two sides and the included angle are equal

• By showing two angles and a non-included side are equal

What property of isosceles triangles can be used to prove that two sides are congruent?

• All angles are 90 degrees

• The triangle is scalene

• Base angles are equal

• All sides are different

If angle 1 is congruent to angle 2 in a triangle, what can be inferred about the sides opposite these angles?

• They are congruent

• They are parallel

• They are unequal

• They are perpendicular