Today's Class 12/05/09

Today Mrs. Saatkamp started the class by going over the hw assigned yesterday (pg. 604 #14-29) that was about areas of right pyramids and right cones. These are some of the problems people had with the hw.

24. Find the lateral and surface are of the regular pyramid.



how to find the slant height:


Lateral Area:


You can also use pythagorean theorem to find the height of the base which is 10.3923 cm. Since you have the base and the height, you can calculate the area of the base which will be 62.3538 cm squared.To find the surface are of the pyramid you do the next:





28. find the surface area of the solid. Imagine that this pyramid has another pyramid undern it and so the bases don't exist. For this question, you had to find the lateral area and multiply it by two.






After we finished correcting the hw, we moved on to the new lesson (this lesson will not be on the quiz tomorrow!!) First Mrs. Saatkamp explained what volume is with the example of the pile of books. She also explained a principle of solids that states:

• If a right and an oblique prism share the same are of the base and the same height, their volumes will be the same but their surface areas will not.

Volume of prisms

where: B= area of base
h= height of the prism

Volume of cylinders

where:
h= height of the cylinder

The units for volume is always cubed!

Then Mrs. Saatkamp assigned homework that is not due until Thursday. The hw is pg. 611 #14-28 all. Dont forget to study for tomorrow's quiz and good luck :]