Question

If the scale factor of figure a to figure b is 7:2 find the perimeter of figure a whenever the perimeter of figure b is 35

Answer 1

122.5

Explanation:

The scale factor of two figures is the ratio of the corresponding sides or in this case the perimeters. The scale factor of figure a to figure b is 7:2 this means that for 7 units of perimeter on the a figure, there are 2 units of perimeter on the b figure.

To obtain the perimeter of the figure a we arrange the equation (the ratio is maintained so both sides of the equation are equal):

`(7)/(2)=(x)/(35)`

where x will be the perimeter of figure a. We solve for a like this:

`x=(35*7)/(2)=122.5`

a figure perimeter is 122.5

Answer 2

a 7 P

-------= --------

b 2 35

Using cross products

7*35 = P*2

P = 7*35/2

P = 122.5