4th Grade - Equilateral, Isosceles And Scalene Triangles

 
     
 
     
 
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4th
Shapes and Geometry
Equilateral, Isosceles and Scalene Triangles
Know the definitions of different triangles (i.e. equilateral, isosceles, scalene) and identify their attributes.
Describe and identify the three types of triangles (equilateral, isosceles, and scalene).
 

Sample Problems

(1)

Classify the triangle. _____________


(equilateral)

(2)

Classify each triangle by the length of its sides:

8 cm, 6 cm, 3 cm _______________


(scalene)

(3)

Find the perimeter of the triangle and classify

Perimeter: _______

Type of triangle: ______________


(P= 14 in.; Isosceles)

(4)

Use an interactive ruler to measure the triangle, then classify:

________ cm Type of triangle: __________


(scalene; measurement depends on type of ruler)

(5)

The lengths of my sides are: 5 in., 12 in., 12 in.

What type of triangle am I? __________


(Isosceles)

Learning Tips

(1)

Math Vocabulary

Equilateral triangle- a triangle with 3 sides congruent


Isosceles triangle- a triangle with two sides congruent


Scalene triangle- a triangle with no sides congruent


Congruent- having the same size and shape


Perimeter- the distance around a figure

(2)

Review how to measure lines (or items) using a ruler:

Most kids begin the measurement at 1 on the ruler. Remind them to start at the tip of the ruler. Practice measuring various lines and remember to write the unit (cm, m, in. etc.) at the end.

(3)

Review Perimeter

The formula to calculate the perimeter for triangles is (Perimeter = a + b + c)

(4)

Tangrams

Use tangrams that have the various types of triangles and sort them on a construction paper mat that has a chart for scalene, equilateral, and isosceles triangles.

(5)

Identify triangles

Have the child look around the house and find objects that have triangular shapes. Invite them to play a game of naming the types of triangles that they find.

Extra Help Problems

(1)

Classify the triangle __________


(Equilateral)

(2)

Classify the triangle _______________

(Scalene)

(3)

Classify the triangle ________________


(Isosceles)

(4)

Classify the triangle _______________




(Equilateral)

(5)

Classify the triangle _________________

(Scalene)

(6)

Classify the triangle ___________________

(Isosceles)

(7)

Find the perimeter.

P= ______


(24m; equilateral)

(8)

Find the perimeter.

P= ___________

(P= 19cm; scalene)

(9)

Find the perimeter.

P= _________


(P= 18 cm; isosceles)

(10)

Find the perimeter.

P= _________


(P= 24 in. ; scalene)

(11)

Find the perimeter.

P = __________


(18 cm; equilateral)

(12)

Use an interactive ruler and measure the sides. Classify the triangle.

(scalene)

(13)

Use an interactive ruler and measure the sides. Classify the triangle.

(isosceles)

(14)

Use an interactive ruler and measure the sides. Classify the triangle.




(equilateral)

(15)

Use an interactive ruler and measure the sides. Classify the triangle

(isosceles)

(16)

If I am an isosceles triangle, what will be the length of my third side:

13 cm, 9 cm, ____cm


  1. 17 cm

  2. 9 cm

  3. 13 cm

  4. b or c


(d)

(17)

If I am an equilateral triangle, what will be the length of my third side:

18 ft., 18 ft., _____

(a) 12 ft.

(b) 18 ft.

(c) 4 ft.


(b)

(18)

If I am a scalene triangle, what will be the length of my third side:

14 in., 13, in., ____ in.

(a) 14 in.

(b) 13 in.

(c) 17 in.


(c)

(19)

If I have two congruent sides, what triangle am I?


(Isosceles)

(20)

If I have three congruent sides, what triangle am I?


(equilateral)

(21)

If I have 3 acute angles, what triangle am I?


(equilateral)

(22)

Explain congruent sides: _________________


(all sides are equal)

(23)

Describe an equilateral triangle:__________


(a triangle with 3 equal (congruent) sides)

(24)

Describe an isosceles triangle: ___________


(a triangle with 2 equal (congruent) sides)

(25)

Describe a scalene triangle.


(a triangle with no equal (congruent) sides)

 

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