hs
r
A cone has two parts, namely the base and the lateral.
h is the height of the cone, r is the radius of the base, and s is the slant height.
Lateral
Base
r
Lateral
Base
Element of Cone
s
h
r
Flat Top
Flat Base
Lateral
Flat Top
Lateral
Flat Base A cylinder has three parts, namely the flat top, flat base and the lateral. h is the height of the cylinder and r is the radius of the base.
Element of Cylinder
SURFACE AREA OF CYLINDER Look at the net of the cylinder below. The total
surface area can be found by adding all the three areas.
SURFACE AREA OF CONE A cone has two parts, namely the base and
the lateral.
On Figure, t is the height of the cone, r is the radius of the base, and s is the slant height.
If the cone is cut along the slant s and its base, we will get the cone net which consists of sector which has radius s and a circle with radius r, as shown:
SURFACE AREA OF SPHERE How do you find the surface area of a
sphere? The surface area of sphere same with
the lateral of Cylinder.
Surface area of Sphere = Lateral area of cylinder
= 2πrh= 2πr X 2r
S = 4πr₂
FIND THE FORMULA
Do you remember about the formula of pyramid?
Volume of pyramid = 1/3 x Area of Base x Height
Because the cone base is a circle with radius r, then Area of Base = π r 2
FIND THE FORMULA
Actually the cone is a pyramid, because have top point. (titik
puncak) and altitude.But the cone’s base is a circle with radius r, So the Area of Circle = π r 2 (base of cone)
FIND THE FORMULA
From this process so the volume of cone is same as volume of
pyramid.
Volume of cone = 1/3 Area of Base x Height = 1/3 x π r 2 x h
Therefore the Volume of Cone = 1/3 π r 2 h
Volume of Cylinder
Actually the cylinder is a prism, because the base and top side are parallel and congruent. But the cylinder have base a circle
Let’s we see this pictures
So the volume of prism = volume of cylinder
Can you compare them ?
Volume of Cylinder =
Volume of Prism =
Hence the volume of cylinder = π r 2 x h
Area of Base x Height
= r.r x h
=
Area of Base x Height
π r 2 x h
Because the cylinder’s base is a circle so the base area is r.r
Find the Volume of Sphere
Prepare the instrument and materials : Scissor, Cutter,
Rice, Plastic ball
1. Cut the ball become 2 parts
4. Repeat until all of hemisphere is full flat. And note it.
3. Fill the cone by rice until full flat. And pour to the one of hemisphere
2. Make a cone by the height and the radius same with radius of ball
The ways...........
Volume of Sphere
From theis activity we see that volume of rice
that poured to hemisphere is not change.
It means that the volume of hemisphere = 2
times of coneVolume of cone = 1/3 π r 2 h(h=r)
= 1/3 π r 2 r
Volume of hemisphere = 2 x 1/3 π r 2 rso
Volume of Sphere = 4 x 1/3 π r 2 r
= 4/3 π r 3
Design The Cone Picture
1. Make an ellipse
2. Find and mark the
centre point of ellipse
3. Make an altitude
4. Mark this end point of
altitude by O.
5. Connect the O lie
ellipse
r
o
Design The Cylinder Picture
1. Make an ellipse
2. Make parallel line that
lie side of ellipse
3. Make ellipse once
again to upward.
Top Related