If we have a rectangle measuring 2cm x 3cm, the perimeter is 10 cm and the area is 6cm squared. (rectangle far left)
If we have a like form, that is 2 times as large, the perimeter will be 10x2, and the area will be 6 x 2 x 2 (or 6 x 2squared, or 6x4=24). This is because the area becomes twice a big in two directions. Following this logic, the rectangle to the right is 4 times as large as our original rectangle. So the perimeter is 10x4=40cm, and the area is 6x4x4 (or 6x16) We can check our answers by drawing the shape, with the correct number of units for the side lengths. Chapter 9 (lessons 1-3), looks at the area of a parallelogram, triangle and trapezoid. Below is a video that reviews what we looked at in class. For additional examples and explanation, go to this website: Study.com |