Question

1 - 41. throughout this book, key problems have been selected as “checkpoints.” each checkpoint problem is marked with an icon like the one at left. these checkpoint problems are provided so that you can check to be sure you are building skills at the expected level. when you have trouble with checkpoint problems, refer to the review materials and practice problems that are available in the “checkpoint materials” section at the back of your book. this problem is a checkpoint for area and perimeter of polygons. it will be referred to as checkpoint 1. show your work. be sure to include the correct units in your answer. a. 12 cm 8 cm perimeter area b. 5 in. 4 in. 11 in. 9.05 in.

Explanation:

Step1: Calculate perimeter of rectangle (a)

Perimeter of rectangle formula is $P = 2(l + w)$. Here $l = 12$ cm and $w = 8$ cm. So $P=2(12 + 8)=2\times20 = 40$ cm.

Step2: Calculate area of rectangle (a)

Area of rectangle formula is $A=l\times w$. So $A = 12\times8=96$ $cm^{2}$.

Step3: Calculate perimeter of triangle (b)

Perimeter of triangle is sum of side - lengths. Sides are 5 in, 9.05 in and 11 in. So $P=5 + 9.05+11 = 25.05$ in.

Step4: Calculate area of triangle (b)

Area of triangle formula is $A=\frac{1}{2}\times base\times height$. Base is 11 in and height is 4 in. So $A=\frac{1}{2}\times11\times4 = 22$ $in^{2}$.

Answer:

a. Perimeter: 40 cm, Area: 96 $cm^{2}$
b. Perimeter: 25.05 in, Area: 22 $in^{2}$