Tuesday, October 5, 2010

Binesi's Blog Post

Today in class I was assigned question 9 to do for the blog.

Examine the bookshelf. It is constructed of thin hardwood. The top, bottom, and all three shelves are the same size. There is an equal distance between the top, the shelves, and the base.

a) What is the surface area of one shelf?
A= l x w (2)
A= 90 x 24 (2)
A= 4 320 cm

You have to multiply by two because theres both a top and bottom in the smaller inside shelf.

b) What is the total surface area of the bookcase?
For the tops and undersides of the entire bookshelf you have to go Length x Width x 10

I got the 10 because there are 5 identical surfaces (add both sides of them equals 10)

The sides of shelves (There are 2 but you have to do both sides)
120 x 24 x 4 = 11 520cm

The very back of the shelf (Multiplied by 2 both sides)
90 x 120 x 2 = 21 600

You add all of the pieces together :
TSA= 21 600+11 520+21 600
TSA= 54 720cm

c) What is the fewest number of surfaces for which you need to find the surface area in order to answer part b?

Only 3 (the back, the small inner shelf and the side shelf)


  1. Good job Binesi! This question is pretty hard but you still explained it. I don't know if you made any mistakes coz I don't get this question :P

  2. Good job binesi. I like how you explained the questions and it doesnt look to me like there are any mistakes.