Triangle Classification and Properties

In this lesson, Justin teaches how to classify triangles by their angles and sides. The video covers the Triangle Sum Theorem and explains different types of triangles, such as acute, right, obtuse, equiangular, scalene, isosceles, and equilateral. Students are guided through example problems and encouraged to complete activities to reinforce their understanding.

What is the purpose of the Triangle Sum Theorem activity?

• To practice cutting out shapes

• To memorize the names of different triangles

• To understand that the angles in a triangle add up to 180 degrees

• To learn how to draw triangles

If a triangle has angles of 45°, 45°, and 90°, what type of triangle is it based on its angles?

• Obtuse

• Right

• Equiangular

• Acute

What do you call a triangle with all angles measuring 60°?

• Equiangular

• Isosceles

• Scalene

• Right

Which type of triangle has all sides of different lengths?

• Equilateral

• Right

• Isosceles

• Scalene

What does the isosceles triangle theorem converse help us determine?

• The triangle's perimeter

• The triangle's area

• The congruence of angles

• The congruence of sides

In a triangle with sides 3, 4, and 5, what type of triangle is it based on its sides?

• Equilateral

• Right

• Isosceles

• Scalene

How do you find the missing side of a right triangle?

• Using the Isosceles Triangle Theorem

• Using the Pythagorean theorem

• Using the Triangle Sum Theorem

• Using the Equilateral Triangle Theorem

If a triangle has two sides of equal length and a right angle, what is it called?

• Acute isosceles

• Right scalene

• Right isosceles

• Equilateral

In a triangle with angles 73°, 73°, and 34°, what type of triangle is it based on its angles?

• Equiangular

• Acute

• Right

• Obtuse

What is the classification of a triangle with two congruent sides and all angles less than 90°?

• Right isosceles

• Acute isosceles

• Obtuse isosceles

• Equilateral