What is an Included Angle - Congruent Triangles

The video tutorial explains the concept of an included angle, which is the angle between two sides of a triangle. It discusses the importance of included angles in determining triangle congruence, specifically using the side-angle-side (SAS) rule. The tutorial highlights common mistakes made when identifying included angles and emphasizes the necessity of having the angle between the two sides for congruence. The video also covers the side-side-side (SSS) rule for congruence and stresses the importance of equal side lengths and angles in congruent triangles.

What is an included angle?

• An angle that is outside the triangle

• An angle that is between two sides

• An angle that is equal to 90 degrees

• An angle that is larger than 180 degrees

Which of the following is necessary for two triangles to be congruent under the Side-Angle-Side criterion?

• The triangles must be right-angled

• The included angle must be between the two sides

• All angles must be equal

• All sides must be equal

What does the Side-Angle-Side criterion require?

• Two angles and a side

• Two sides and a non-included angle

• Three sides of equal length

• Two sides and the included angle

Why might a triangle not meet the Side-Angle-Side congruence criterion?

• The angle is not between the two sides

• The triangle is not equilateral

• The sides are not parallel

• The angle is larger than 90 degrees

What is a common mistake when identifying included angles in triangles?

• Assuming any angle is included

• Focusing only on the angles

• Assuming all triangles are congruent

• Ignoring the length of the sides