Understanding Isosceles and Equilateral Triangles

This video tutorial reviews isosceles and equilateral triangles, focusing on their properties and how to use these properties to find missing angles. It begins with a recap of previous lessons on isosceles triangles, emphasizing the congruency of base angles. The tutorial then demonstrates solving for missing angles using given properties and concludes with a word problem that applies these concepts. The video encourages drawing diagrams to visualize problems and reinforces the importance of identifying congruent angles.

What is a key characteristic of an equilateral triangle?

• All angles are 90 degrees.

• It has one right angle.

• All sides are different lengths.

• All sides and angles are equal.

In an isosceles triangle, which angles are congruent?

• The angles opposite the equal sides.

• The angles adjacent to the base.

• All three angles.

• None of the angles.

If one angle of an isosceles triangle is 30 degrees, what is the measure of each base angle?

• 60 degrees

• 75 degrees

• 45 degrees

• 90 degrees

In the example problem, if the top angle is 25 degrees, what are the measures of the base angles?

• 75 degrees each

• 25 degrees each

• 30 degrees each

• 50 degrees each

In the word problem, which sides are congruent in triangle RST?

• RT and ST

• RS and RT

• None of the sides

• RS and ST

What is the value of X in the word problem involving triangle RST?

• 3

• 4

• 6

• 5

What is the measure of angle R in the word problem after solving for X?

• 50 degrees

• 47 degrees

• 55 degrees

• 45 degrees

What is the measure of angle S in the word problem after solving for X?

• 45 degrees

• 47 degrees

• 55 degrees

• 50 degrees

What is the measure of angle T in the word problem after solving for X?

• 86 degrees

• 80 degrees

• 82 degrees

• 84 degrees

What should you do first when solving a word problem involving triangles?

• Guess the angles.

• Find the area.

• Calculate the perimeter.

• Draw a picture of the triangle.