(1) Form of an object - how it is laid out in space
(not what it is made of, or where it is).
(2) Perimeter : the length of
the sides forming the shape, or
the distance of the
closed figure
(3) Area: the amount of surface that is enclosed by
the shape.
Name the Shapes
2D and 3D Shapes
SQUARE
(1) 4-sided
figures , 4
equal sides
(length of all sides are equal)
Perimeter and Area
Perimeter = S + S + S + S Area
= S x S
= 4 x S = S2 cm2
= 4S
cm
Example:
What are the perimeter and area of figure A?
Method:
Step1: Circle/Underline Keywords. Draw(if need be) and Trace shape
< Perimeter – use
finger to trace the outline, area-finger to go over the area>
Step2: What is the formula for this shape? (Perimeter=4
x A, Area = A x A)
Step3: Use the formula to calculate the required
measurement
Perimeter = 4xSide = 4 x 7 = 28 cm
Area = side x Side = 7 x 7 = 49cm2
Example:
Linda bent a wire 32 cm long into a square. What is the length of the
side of the square?
Step1: Trace and
draw what’s required
Wire = 32cm
Step2: What is
the formula for this shape? (Perimeter=4 x A)
Step3: Use the
formula to calculate the required measurement
Perimeter = 32 cm = 4 x Side
Length of side = 32 ÷ 4 = 8cm
Example
What is the perimeter of the square
when the area is 36cm2?
Step 1 : Circle/Underline Keywords, draw a square, and write Area = 36cm2
Step2: Formula for the shape?
(Area
= S x S, Perimeter=4S)
Step3: Solve
Area
= 36cm2
Side
= 6cm
Perimeter = 4 x 6cm = 24cm
Common Number Square that Learners need to know:
RECTANGLES
(1)
4-sided figure/shape
(2)
Opposite sides are equal
(3)
Opposite sides are parallel to each other
(4)
It has 4 right
angles
(5)
Longer side is called the length, shorter
side is called the breadth
Perimeter and Area
Perimeter Area
= length + breadth + length + breadth =
Length x Breadth
= 2 x Length + 2 x
Breadth = L x B
= 2 (Length +
Breadth)
PERIMETER = 2 (L + B) AREA = L x B
Note: Squares and Rectangles are special quadrilateral
<<< tri ~ 3 , quad ~ 4, cir ~ round >>>
Example:
Find the perimeter and area of the rectangle.
Step1: Circle/Underline Keywords. Draw and
Trace what’s required
<
Perimeter – use finger to trace the outline, area-finger to go over the
area>
Step2: Formula for this shape? Perimeter=2(L+B), Area = L X B
Step3: Solve: Use the formula to calculate the required
measurement
Perimeter =
2 x (L + B)
= 2 x (4+6)
= 2 x 10 cm = 20
cm
Area
= L x B = 4 x 6
= 24 cm2
Example:
The perimeter of a rectangle is 28cm. Its length is
8cm. Find its breadth and area.
Step1:
Trace/Draw what is required
< The student draws the rectangle and fill in
the required details – length = 8cm, perimeter=28cm>
Step2: What is
the formula for this shape? Perimeter=2(L+B), Area = L X B
Step3: Use the
formula to calculate the required measurement
Perimeter = 2 X (L + B)
28cm = 2 (8 + B)
28 / 2 = 8 + B
14
= 8 + B
B = 14 – 8 = 6 cm
Area = L X B = 8 cm x 6 cm
= 48cm2
Example
Step1: Trace/Draw what is
required
< GF = AB, GE = GF + FE, BC = AG – CF(=DE), Angle GAB = 90o
>
Step2: What is the formula for
this shape? <All sides of square are
equal>
Step3: Use the formula to
calculate the required measurement
CDEF = square
FE = DE = 8 cm
GE = GF + FE = 15 + 8 = 23 cm
BC = BF – CF
BF = AG = 12cm
CF = DE = 8cm
BC = 12 – 8
= 4 cm
{Angle P = 90 – 18 – 36 = 36o}
~~~~ END ~~~~ :)
~~~~ END ~~~~ :)
