When the length of one of the sides is multiplied by a constant the effect is to multiply the original volume by that constant, as for the example in
[link] .
Right pyramids, right cones and spheres
A pyramid is a geometric solid that has a polygon base and the base is joined to a point, called the apex. Two examples of pyramids are shown in the left-most and centre figures in
[link] . The right-most figure has an apex which is joined to a circular base and this type of geometric solid is called a cone. Cones are similar to pyramids except that their bases are circles instead of polygons.
Surface Area of a Pyramid
The surface area of a pyramid is calculated by adding the area of each face together.
If a cone has a height of
$h$ and a base of radius
$r$ , show that the surface area is
$\pi {r}^{2}+\pi r\sqrt{{r}^{2}+{h}^{2}}$ .
The cone has two faces: the base and the walls. The base is a circle of radius
$r$ and the walls can be opened out to a sector of a circle.
This curved surface can be cut into many thin triangles with height close to
$a$ (
$a$ is called the
slant height ). The area of these triangles will add up to
$\frac{1}{2}\times $ base
$\times $ height(of a small triangle) which is
$\frac{1}{2}\times 2\pi r\times a=\pi ra$
$a$ can be calculated by using the Theorem of Pythagoras. Therefore:
A triangular pyramid is placed on top of a triangular prism. The prism has an equilateral triangle of side length 20 cm as a base, and has a height of 42 cm. The pyramid has a height of 12 cm.
Find the total volume of the object.
Find the area of each face of the pyramid.
Find the total surface area of the object.
We use the formula for the volume of a triangular prism:
To find the total surface area, we must subtract the area of one face of the pyramid from the area of the prism. We must also subtract the area of one of the triangular faces of the prism. Doing this gives the total surface area as:
$1120-420+1680-420=1960$ This is the answer to part c.
Calculate the volumes and surface areas of the following solids: *Hint for (e): find the perpendicular height using Pythagoras.
Water covers approximately 71% of the Earth's surface. Taking the radius of the Earth to be 6378 km, what is the total area of land (area not covered by water)?
Questions & Answers
where we get a research paper on Nano chemistry....?
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest.
Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.?
How this robot is carried to required site of body cell.?
what will be the carrier material and how can be detected that correct delivery of drug is done
Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?