Rectangle, Square, Perimeter of Rectangle, Square
1.1. Rectangle
 Rectangle ABCD has :
 The four vertices A, B, C, and D are all right angles.
 4 sides include: 2 long sides are AB and CD, 2 short sides are AD and BC.
Two long sides have the same length, written as: AB = CD.
The two short sides have the same length, written as: AD = BC.
 A rectangle has 4 right angles, 2 equal long sides and 2 equal short sides.
 The length of the long side is called length, the length of the short side is called width.
1.2. Square
 Square ABCD has :
 The four vertices A, B, C, and D are all right angles.
 4 sides of equal length.
AB = BC = CD = DA.
 A square has 4 right angles and 4 equal sides.
1.3. Perimeter of a rectangle
 The perimeter of rectangle ABCD is :
4 + 3 + 4 + 3 = 14 (cm)
or (4 + 3) x 2 = 14 (cm)
 To calculate the perimeter of a rectangle, we take the width plus the length (same unit of measure) then multiply by 2.
1.4. Square Perimeter
 The perimeter of square ABCD is :
3 + 3 + 3 + 3 = 12 (cm)
or 3 x 4 = 12 (cm).
 To calculate the perimeter of a square, multiply the length of one side by 4.
1.5. Solve textbook exercises pages 84, 85
Lesson 1: Which of the following figures is a rectangle?
Solution guide:
 The MNPQ figure and the RSTU figure are rectangles.
 Figure ABCD and figure EGHI are not rectangles.
Lesson 2: Measure and then state the lengths of the sides of each of the following rectangles
Solution guide:
 Using a ruler, measure the lengths of the four sides of the given rectangle.
Using a ruler to measure the sides of the rectangles, the result is as follows:
+ Rectangle ABCD has: AB = CD = 4cm
AD = BC = 3cm
+ Rectangle MNPQ has: MN = PQ = 5cm
MQ = NP = 2cm
Lesson 3: Find the length and width of each rectangle in the figure below
(DC = 4cm; Patient = 1cm; NC = 2cm).
Solution guide:
 Identify the rectangles included in the given shape.
 Based on knowledge: Rectangles have equal length and equal width to find the lengths of the sides.
+ Rectangle ABMN has length AB = MN = 4cm and width AM = BN = 1 cm
+ Rectangle MNDCMNCD has length MN = DC = 4cm and width MD = NC = 2cm.
+ Rectangle ABCDABCD has length AB = DC = 4cm and width AD = BC = 1cm+2cm = 3cm.
Lesson 4: Draw a line to get a rectangle
Solution guide:
 Using a ruler and pencil, draw a suitable line into the given shape to form a quadrilateral with four right angles, two equal length sides and two equal short sides.
You can add a straight line as shown below:
1.6. Solve the textbook exercises pages 85, 86
Lesson 1: Which of the following figures is a square?
Solution guide:
 Find a quadrilateral with four right angles and four equal sides.
+ EGHI is a square because it has 4 right angles and 4 equal sides.
+ Figure ABCD and figure MNPQ are not squares.
Lesson 2: Measure and then state the length of each of the following squares
Solution guide:
 Use a ruler to measure the lengths of the sides in the given square.
The length of the side of square ABCD is 3cm
The side length of square MNPQ is 4cm
Lesson 3: Draw a line to get a square ?
Solution guide:
 Add a line segment to the given shape so that the number of squares on each side is equal and the new shape has 4 right angles.
You can add a line like this:
Lesson 4: Draw according to the following pattern
Solution guide:
Draw according to the given pattern.
1.7. Textbook exercise solution page 87
Lesson 1: Calculate the perimeter of a rectangle with
a) Length 10cm, width 5cm;
b) Length 2dm, width 13cm.
Solution guide:
 To calculate the perimeter of a rectangle, we take the length plus the width (same unit of measure) and then multiply by 2.
a) Perimeter of the rectangle is: (10+5)×2 = 30(cm)
b) Change: 2dm = 20cm
The perimeter of the rectangle is: (20+13)×2 = 66(cm).
Lesson 2: A rectangular piece of land has a length of 35m and a width of 20m. Calculate the perimeter of the land.
Solution guide:
 To calculate the perimeter of a rectangle, we take the length plus the width (same unit of measure) and then multiply by 2.
Solution
Perimeter of rectangular land is:
(35+20)×2 = 110(m)
Answer: 110m.
Lesson 3: Circle the word in front of the correct answer
A. The perimeter of rectangle ABCD is larger than the perimeter of rectangle MNPQ.
B. The perimeter of rectangle ABCDABCD is less than the perimeter of rectangle MNPQ.
C. The perimeter of rectangle ABCDABCD is equal to the perimeter of rectangle MNPQ.
Solution guide:
 Calculate the perimeter of rectangles ABCD and MNPQ.
 Compare and choose the correct answer.
Perimeter of rectangle ABCD is :
(63+31)×2 = 188 (m)
Perimeter of rectangle MNPQ is equal to :
(54+40)×2 = 188(m)
Perimeter of rectangle ABCD is equal to perimeter of rectangle MNPQ.
Circle the letter C.
1.8. Textbook exercise solution page 88
Lesson 1: Write in the blank (according to the form)
Square edge 
8cm 
12cm 
31cm 
15cm 
Square Perimeter 



Solution guide:
 To calculate the perimeter of a square, multiply the length of one side by 4.
Square edge 
8cm 
12cm 
31cm 
15cm 
Square Perimeter 
8 x 4 = 32(cm) 
12 x 4= 48 (cm) 
31 x 4 = 124 (cm) 
15 x 4 = 60 (cm) 
Lesson 2: People bend a piece of steel wire just enough to form a square of side 10cm. Calculate the length of that string.
Solution guide:
 To calculate the length of a string, multiply the length of one side of the square by 4.
Solution
The length of that string is:
10×4 = 40(cm)
Answer: 40cm.
Lesson 3: Each square brick has a side of 20cm. Calculate the perimeter of the rectangle made up of 3 such bricks (see figure) ?
Solution guide:
 Find the length of the rectangle joined by 3 square bricks.
 Find the perimeter of a rectangle: Take the length plus the width (same units) and multiply by 2.
Solution
The length of the rectangle is:
20×3 = 60(cm)
Perimeter of the rectangle is:
(60+20)×2 = 160(cm)
Answer: 160cm.
Lesson 4: Measure the side lengths and then calculate the perimeter of the square MNPQ
Solution guide:
 Using a ruler, measure the length of one side of the square.
 The perimeter of a square is equal to the length of one side times 4.
Solution
Measure the length of the side of the square by 3cm.
Perimeter of the square is:
3×4 = 12(cm)
Answer: 12cm.
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