CPM Homework Banner

Home > CC1MN > Chapter 1 > Lesson 1.1.3 > Problem 1-21

1-21.

Find the perimeter of each figure below. The markings on part (b) mean that the lines are parallel. The markings on part (e) show that all sides are the same length. As you find each perimeter, be sure to show your work.

  1. A rectangle with a length of 8 centimeters and a width of 3 centimeters.

  • This shape is a rectangle. Find its perimeter. Remember that the perimeter is the total length of the border around the shape.

  • Find the unknown lengths and label them on your diagram. Now try to find the perimeter without looking at the answer.

  • Be sure to show why the perimeter is cm.

  1. A trapezoid where the two parallel sides are 5 centimeters and 9 centimeters. The other two sides are 3 centimeters each.

  • The perimeter is the total length of the border around the shape.

    The perimeter is . Calculate this sum.

    . Can you show how you arrived at this answer?

  1. A right triangle where the legs are 5 inches and 12 inches. The hypotenuse is 13 inches.

    See (a) and (b).

  1. A triangle with the following sides in millimeters: 3 , 6, and 4.

    See (a) and (b).

  1. A rhombus where all four sides are equal. One of the sides is labeled 4 feet.

    The markings mean that all the sides are long.

    A rhombus where all four sides are equal. All of the sides are labeled 4 feet.

  1. An isosceles triangle where the sides are labeled in meters: 10, 10, and 5.

  • See (a) and (b).

© 2022 CPM Educational Program. All rights reserved.