Head First 2D Geometry

a new mystery shape

260 Chapter 6

Landowners, unite

Just when all the lawns seemed under control, Edward ran into a little snag.

He turned up at a customer’s house to find that he has been buying up

adjacent land. The neat rectangular lawn that Edward had been mowing

for months has been transformed into…something else.

Before:

After:

It’s going to take longer to mow and edge this new lawn, and

Edward needs a hand working out the charges. He took some rough

measurements and gave them to you over the phone, but he didn’t

get all the sides. So what do we do with a lawn like this?

28 meters

24 meters

24 meters

28 meters

53 meters

The lawn was originally a tidy

rectangle. Super easy to mow,

and calculating charges was a

snap!

The lawn is definitely

larger. It still has four

sides, but it’s not a shape

we’ve seen before.

you are here 4 261

quadrilaterals

Check out the shape of the new lawn. How do you think we could

go about finding the area of a shape like this?

Really?

We can’t do exactly the same thing we

did before because we don’t have all the

measurements we’d need. Let’s take a closer

look.

You’ve GOT to be kidding! This

is way too easy, we’ve done all this

before. All we need to do is split the

shape into a rectangle and two triangles,

and find the total area. Duh!