No Warm-Ups This Week

• We will have a test Monday over formulas and area.

Geometry 9-5

Effects of Changing Dimensions Proportionally

Big Idea

• When the dimensions of a figure are changed, the perimeter and area of the figure change proportionally.

• To find out how they change, substitute values into the formulas.

Example

• A rectangle has length, l=4, and width, w=12. What is the effect on the area of the rectangle if…

• The length is tripled?

• The width is doubled?

• The length is tripled and width is doubled?

Example

• Name four different ways the dimensions could change to achieve the following result:– The area of a parallelogram is increased by a

factor of 12.

Example

• Describe the effects of quadrupling the radius of a circle to the:– Circumference– Area