Exercise 12 Page 379

We want to estimate the perimeter and the area of the shaded figure. We can do these things one at a time.

Estimated Perimeter

We can recall that a perimeter is the distance around the outside of a two-dimensional figure. We can approximate the perimeter of our figure by estimating the sum of all of its side lengths. Let's start by considering the given diagram!

Notice that the sides of our figure consist of grid square lengths and no diagonal lengths. We can recall that each grid square length is 1 unit. We can add this information to our diagram.

Now we can calculate the number of grid square lengths. Let's do it!

We found that there are 28 grid square lengths. Finally, we can calculate the length of the perimeter. We can do by multiplying the number of the grid square lengths by the side length of 1 grid square, 1. Perimeter 28* 1=28 The figure has the perimeter of 28 units.

Estimated Area

We want to estimate the area of the composite figure. We can do so by calculating the number of grid squares in our figure. Let's do it!

We found that there are 32 squares with the area of 1 square unit. Finally, we can calculate the area of the figure. We can do so by multiplying the number of grid squares, 32, by 1 square unit. Area 32* 1 =32 The figure has the area of 32 square units.