8-6 P ERIMETERS AND A REAS OF S IMILAR F IGURES M11.C G Objectives: 1) To find the perimeters and areas of similar figures. PDN: Pg. 454 #4-6

THEOREM: PERIMETERS AND AREAS OF SIMILAR FIGURES If the similarity ratio of two similar figures is a/b, then 1) The ratio of their perimeters is a/b and 2) The ratio of their areas is a ²/b²

E XAMPLE : T WO SIMILAR POLYGONS Two similar polygons have corresponding sides in the ratio 4: 8 a) Find ratio of perimeters b) Find the ratio of their areas

C HECK U NDERSTANDING P G. 455 #1A,B

EXAMPLE The ratio of the lengths of the corresponding sides of two regular octagons is 8/3. The area of the larger octagon is 320 ft ². Find the area of the smaller octagon.

C HECK U NDERSTANDING P G. 455 #2

E XAMPLE : F INDING S IMILARITY & P ERIMETER R ATIOS The areas of two similar pentagons are 32 in ² and 72in². What is their similarity ratio? What is the ratio of their perimeters?

C HECK U NDERSTANDING P G. 456 #4