Lesson Page

Math A

Similar Polygons - Ratio of Perimeters
& Areas


Ratio of Sides, Perimeters, etc.

If two polygons are similar, their corresponding sides, altitudes medians, diagonals, and perimeters are all in the same ratio.

Rule: s = side, p = perimeter, a = altitude, m = median
1 = first polygon, 2 = second polygon
Example:
If the sides of two similar triangles are in the ratio 4:9, what is the ratio of their perimeters?

Answer:  4:9

 

 

Ratio of Areas

If two polygons are similar, the ratio of their areas is equal to the square of the ratio of their corresponding sides.

Rule: A = area, s = side
1 = first polygon, 2 = second polygon
   also.............
Example:
If the sides of two similar triangles are in the ratio of 3:5, find the ratio of their areas.

Answer:  9:25

 

 


Caldwell