Isosceles and Equilateral Triangle

• Mathematics
• Primary Education
• Age 5,12,13

Isosceles and Equilateral Triangle

Classification of triangle

wordwall.net

Priya is designing a decorative wall hanging in the shape of an isosceles triangle. The two equal sides are made of wooden sticks, each 50 cm long. The base of the triangle is a fabric strip, and she wants to ensure that both angles at the base are equal to keep the design symmetrical.

If the angle between the two wooden sticks at the top (vertex angle) is 40°, what is the measure of each of the base angles?

Learning Objective

• Develop and apply the isosceles and equilateral triangle properties.

• Relate the concept to real-life situations.

ACTIVITY

Conclusion....

Which of the following triangles has two equal angles?

1. Scalene triangle
2. Equilateral triangle
3. Isosceles triangle
4. Right triangle

Each angle in an equilateral triangle measures ________ degrees

1. 120 degree
2. 60 degree
3. 180 degree
4. 360 degree

Priya is designing a decorative wall hanging in the shape of an isosceles triangle. The two equal sides are made of wooden sticks, each 50 cm long. The base of the triangle is a fabric strip, and she wants to ensure that both angles at the base are equal to keep the design symmetrical.

If the angle between the two wooden sticks at the top (vertex angle) is 40°, what is the measure of each of the base angles?

Shown in the figure is an isosceles triangle. Work out the size of the angle marked y.

1. 20 degree
2. 26 degree
3. 60 degree
4. 180 degree

AFL-Find value of w

Find the value of w in the given figure

Extension/ HW

a) Find at least two famous real-world structures (buildings, monuments, bridges, art, etc.) that use isosceles or equilateral triangles in their design.

b) Identify which type of triangle is used (isosceles or equilateral).

c)Explain why that type of triangle has been chosen?

ASSET

Find x, if the triangle in the given figure is isosceles triangle.

a) x= 12                 b) x= 13                  

c) x = 10                    d) x= 11