Lesson 4: The circumference of the triangle and its area -For the fifth grade.

Lesson 4: The circumference of the triangle and its area 
محيط المثلث ومساحته       

Lesson ideas:
1) Recognize the head of the triangle and rise
Triangle, triangle base and triangle circumference
2) Find the circumference of the triangle if you know the lengths of the ribs
3) Solving issues on the perimeter of the triangle
4) Find the area of the triangle in square units and infer the law of its area
5) Find the area of the triangle
6) Solve issues over the area of the triangle
7) Various examples

Part 1: Recognize the head of the triangle and rise
Triangle, triangle base and triangle circumference

Note: The triangle is a triangular polygon with 3 heads, three corners and three sides
And each triangle has a base and a height.
The base of the triangle is: the side on which the column is drawn or the length of it.
The height of the triangle is: the length of the column drawn from one of the heads of the triangle to the opposite side or to its extension.

The circumference of the triangle is the sum of the lengths of the ribs.
As we know, each triangle has three sides, so if we add these lengths, it's the circumference of the triangle.

Part 2: Finding the circumference of the triangle if you know the lengths of its ribs

Example (1): Find the circumference of each of the following triangles:

1) Triangle of lengths of ribs (5.6 cm), (7cm) as well as (2.3cm) what is its circumference?

2) Triangular plate, lengths of its ribs (2)m  (1.7)m (1.7) m, it is meant to be surrounded by a frame, what is the length of this frame?

Part 3: Solving issues on the perimeter of the triangle

Example (2): Resolving the following issues:
Example (2): Resolving the following issues:
1) Kamal has a triangular plot of land, lengths
 2 km, 2 km, 3 km, he wants to surround her with a fence:
A. How long is the fence
B- If the cost per meter of the fence is $30, what does the cost of the entire fence?

Part 4: Finding the area of the triangle in square units and inferring the law of its area

Note:
Triangle area = half the length of the base x height

Example (3): Use the following forms of table fill:

Half the length of the base x height	Height	Base length	Triangle area by number of square units	Shape
				1
				2
				3

Note:
The graphics you find in the pictures 

Part 5: Finding the area of the triangle

Example (4): Find the area of each of the following triangles:

1) Triangle base length (16)m
 And his height is 12 meters.

Note:
There are additional examples in the pictures. 

Part 6: Solving issues over the area of the triangle

Example (5): Answer the following questions:
1) Triangular land, base length (2) km
And its height (half) km    how much if the price per square meter of land (500)dollars, what is the price of the land?

2) Khaleda spun a triangular-shaped rug
 Its base is 150 cm high, and it's 100 cm high.