Transcript Area of Shapes

Area of Shapes
 The area of a shape is the space it occupies.
 Write down the name of each shape.
Parallelogram
Trapezoid
Square
Rectangle
Triangle
Circle
Area of Shapes
 Click button to select topic.
Square
Rectangle
Parallelogram
Triangle
Trapezoid
Circle
End Show
The Square
Area = l x l
l
length
e.g. Find the area of a square whose
side is 3.5 cm.
A = l x l Discuss
and work out
A = 3.5this
cm example
x 3.5 cm
together
= with
12.25your
cm2 friend.
The Rectangle
Area = l x w
w
l
e.g. Find the area of a rectangle that
has a length of 3.5 cm and a height of
80 cm.
Since units must be the same:
Discuss
A = l x and
w work out
A = 3.5this
cm example
x 80 cm
2
= 280 cm
together.
The Parallellogram
Area = b x h
e.g. Find the area of the parallelogram
below to the tenths.
h
height
3.8 cm
10.3 cm
b
base
A = b Discuss
xh
A =and
10.3
cm out
x 3.8 cm
work
=this
39.14
cm2
example
= 39.1
cm2
together.
h
b
The Triangle
Area = ½ b h
e.g. Find the area of triangle ABC
to the nearest whole cm.
A
h
height
b
base
4 cm
B
11.7 cm
A = ½b
xh
Discuss
A =and
½ work
x 4 cmout
x 11.7 cm
h
=this
23.4
cm2
example
b
= 23
cm2
together.
½ area
Area
Area of
of parallelogram
= ½b
 h of= parallelogram
bh
C
The Trapezoid
Area = ½h(a + b)
e.g. Find the area of the trapezoid.
Length aof side a
height
h
Length bof side b
Copy
b
a the trapezium
8.5 cm
6 cm
12 cm
h = 6cm, a = 8.5 cm, b = 12 cm
A about
= ½h(athe
+ b)
Decide
values
h2 trapeziums form a parallelogram
A = ½ x 6 of
cma,xb(8.5
andcm
h + 12 cm)
The
Area
of
1
trapezoid
is
half
h(a
+
b)
Rotate the trapezium
= ½ x to
6 cm
findx the
20.5area.
cm
Area of parallelogram
a = h(a + b)
b
= 61.5 cm2
 Area of trapezoid = ½ h(a + b)
The Circle
Area = p r2
Radius
r
Center
Remember:
the radius
of a circle is
half the diameter.
e.g. The diameter of a circle is 19 cm.
Find the area of the circle to the
nearest cm.
r = 19 cm ÷ 2
= 9.5 cm.
Find the radius first
2
A =and
p rthen
work out
example
= pthis
x 9.5
cm x 9.5 cm
together.
= 283.5
cm2
= 284 cm2
The Circle
Area = p r2
r
e.g. The diameter of a circle is 19 cm.
Find the area of the circle to the
nearest cm.
r = 19 cm ÷ 2
= 9.5 cm.
A = p r2
Remember:
the radius
of a circle is
half the diameter.
= p x 9.5 cm x 9.5 cm
= 283.5 cm2
= 284 cm2
End Show