Sunday, April 22, 2012

Aim: How do we find the volume of pyramids and cones?

To find the volume of a cone you must use the formula (1/3) times pi times the radius squared times the height.





The volume of this figure would be 6 squared (36) time 15 (540) divided by 3 (180). You could leave this answer in terms of pi which would equal 180pi cm cubed.


To find the volume of a pyramid you have to use the formula (1/3) time base times height.







  • The volume of this pyramid would be 8 times 8 (36) times 9 (324) divided by 3 (108). The final answer would be 108 cm cubed.









    Find the volume of theses two solids:


































  • Aim: How do we find the surface area and volume of the sphere?

    To find the volume of a sphere you must use the formula 4 times pi times the radius cubed divided by 3.

    For example:

     

    The volume of this sphere would be 4 cubed (64) times 4 (254). After this you could just leave the problem in terms of pi which is 256pi and  then divide it by 3. The final answer would be 85.3pi cm cubed.




    To find the surface area of a sphere you must use the formula 4pi times radius squared.




     

    Using the same sphere the surface area would be 4 squared (16) times 4 (64). After you find this you could just leave the final answer in terms of pi which is 64pi.




    Find the surface area and volume of this sphere:


    Sunday, April 1, 2012

    Aim: How do we find surface area and lateral aea of prisms and cylinders?

    The formula to find the surface are of a prism is base times height times width



  • For example in this image the base length is 5, the height is 3  and the length is 10.
    5 x 3 x 10 = 150

    And to find the lateral are of this figure would would simply subtract the area of the two faces which would be the area of the two squares.
    3 x 5 x 2 = 30
    Then you would subtract the area of the two faces from the total surface area.
    150-30= 120.
    Lateral area = 120.

     Find the Surface and lateral area of this prism:


    The surface area formula of a cylinder is: 2 π r2 + 2 π r h



    To find the surface area of his cylinder you would do radius squared (9) times 2 times π.
    This will find the area of the two circles. To find the area of the rest of the solid you would have to do
    6 x 3 x 2 x π. 
    This formula would also solve the lateral area.

    But to find the surface area you would have to add the outcome of the first equation and the second equation.


    Find the surface and lateral area of this cylinder:


     








    Aim: How do we idnetify solids?

    Solid- 3- dimensional figures with width, depth and height.

    All solids have volume and surface area.
    There are two types of solids:
    Polyhedra- having all flat surfaces.
    Non- Polyhedra- if any surface is not flat.

    All solids fall under these two categories.

    Figures that would be considered polyhedras are; cubes, pyramids and prisms
    Figures that fall under the category of non-polyhedras are figures like; cylinders or spheres.