December 6, 2012 Notes

Surface Area

       - Area is the number of the square units it takes to cover a surface. Always expressed as squared units.

Formulas for finding the area of a square, rectangle, triangle, and circle.

Finding the perimeter of a given area of a circle. 

    Question: A square has an area of 35 squared centimentres. What is the measure of its perimeter.

Find the area of the given shape.

First way: Finding the area of the whole shape including the missing shape.. Then subtract the area of the missing shape from the whole shape to get the area of the given shape.

Second Way: 

Test Answers #10

 Question: 

          A 1-L can of paint covers 12m². Determine the maximum dimensions of a 

square ceiling you could paint with 3 1/2 L if paint. Express your answer to the 

nearest hundredth of a meter. 

Solution: 

            Hope this helps :)! Let's do better next test guys :D ! 

Textbook pg.79, #15

             

     15. Kai needs to replace the strip of laminate that is glued to the vertical faces on a square tabletop. The tabletop has an area of 1.69m². What length does she need?

            Solution: 

                Explanation:    We are squaring the area of the tabletop because we are trying to find which factors are equivalents to 1.69m² and those factors are the side length of the tabletop.

                ANSWER:  Kai needs 1.3m laminate.

                       

Textbook pg.61, no.16

Question: 

       16.)  Bella is more comfortable working with integers than with positive and negative decimal numbers. This is her way of understanding -4.3 + 2.5 .

•  -4.3 is -43/10 or -43 tenths.

• 2.5 is 25/10 or 25 tenths.

• -43 tenths + 25 tenths is -18 tenths.

• -18 tenths is -18/10 or -1.8 .

• So, -4.3 + 2.5 = -1.8 .

         a.) Use Bella's method to determine 6.1 + (-3.9) .

             Solution:

     

        b.) How could you modify Bella's method to determine
           1.25 - 3.46 ?

                   * Use hundredths instead of tenths to get the answer.

                          Solution: