Determine the missing parts of a polygon and find the perimeter

The video tutorial guides students through finding scale factors and perimeters of polygons. It begins with setting up ratios for proportional sides, solving for unknown side lengths using cross-multiplication, and concludes with calculating the perimeters of the polygons. The teacher emphasizes understanding proportional relationships and applying them to solve geometric problems.

What is the first step in finding the scale factor between two polygons?

• Calculate the perimeter of each polygon

• Set up a ratio between corresponding sides

• Find the area of each polygon

• Measure the angles of the polygons

How do you solve for a missing side length using proportions?

• Multiply the known side by the scale factor

• Divide the perimeter by the number of sides

• Add all the side lengths together

• Set up a proportion and cross-multiply

What is the value of X when 21 is to 15 as X is to 20?

• 14

• 28

• 20

• 15

What is the next step after finding all the missing side lengths?

• Calculate the area of the polygons

• Find the perimeter by adding all side lengths

• Recheck the scale factor

• Compare the angles of the polygons

What is the perimeter of the second polygon given the side lengths 28, 14, 14, 21, and 14?

• 79

• 85

• 91

• 65