Head First 2D Geometry

you are here 4 253

quadrilaterals

…and the customers keep flooding in

I’ve put a new garden

bed in the middle of my lawn

for a ton of colorful flowers.

There’s less lawn to mow, so

can I get a discount?

Another

customer

30 meters

20 meters

4.5 meters

13 meters

These sides are congruent.

These sides are congruent, too.

Check out the sketch of the lawn. How would you calculate just

the area of the lawn, without the flower bed? Describe what you

need to do in words and sketches, and assume you have all the

measurements you need.

sharpen solution

254 Chapter 6

=

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That’s great, but

how do we find the area of

the flower bed? It’s not a

rectangle, and it doesn’t look

like a parallelogram either.

Area of lawn

Area of the main lawn rectangle Area of the

flower bed

=

-

OR

So to find the total area of the lawn we have to mow, we need to find the area of the lawn as

though the flower bed wasn’t there, and then subtract the area of the flower bed.

True, it isn’t a rectangle or a parallelogram.

The opposite sides of the flower bed aren’t parallel. Could you

use a technique from earlier in this chapter to try to figure out

the area of that shape?

Check out the sketch of the lawn. How would you calculate just

the area of the lawn, without the flower bed? Describe what you

need to do in words and sketches, an ...