# Area of Triangles and Rectangles

An error occurred trying to load this video.

Try refreshing the page, or contact customer support.

Coming up next: Circles: Area and Circumference

### You're on a roll. Keep up the good work!

Replay
Your next lesson will play in 10 seconds
• 0:06 Shapes
• 0:47 Rectangles
• 2:40 Right Triangles
• 3:48 Oblique Triangles
• 5:11 Lesson Summary

Want to watch this again later?

Timeline
Autoplay
Autoplay

#### Recommended Lessons and Courses for You

Lesson Transcript
Instructor: Jeff Calareso

Jeff teaches high school English, math and other subjects. He has a master's degree in writing and literature.

How do you find out the area of rectangles and triangles? Learn how in this lesson! We'll look at the formulas, then practice solving problems for each shape.

## Shapes

Rectangles and triangles are all around us... watching us. That's not creepy at all, right? Okay, it's a little creepy. But, they're also around us in less ominous, more friendly ways.

That field where you play soccer or football? That's a rectangle. As is everything from your cell phone to the state of Colorado. And that rack you use to set up the balls on a pool table? That's a triangle. So is the peanut butter and jelly sandwich you cut diagonally because it's more fun to eat that way. They even come in larger sizes, like the pyramids in Egypt. In this lesson, we're going to learn how to find the area of these shapes. Let's start with rectangles.

## Rectangles

Let's say you're planting a garden. If your garden is 12 feet long and 4 feet wide, how big is it? This garden is a rectangle, and what you want to know is its area. The area of a rectangle is the length times the width.

So, your garden is 12 feet long by 4 feet wide. 12 is our length, and 4 is our width. 12 * 4 is 48. So, your garden is 48 square feet. Note the 'square.' That means that there are 48 one foot by one foot squares in your garden. That's plenty of space for your vegetables!

Let's try another. Let's say you've planted your garden, and now you have an abundance of zucchini, so you're making zucchini bread - mmm, tasty. Your bread pan is 9 inches long by 5 inches wide. What is the area? Like your garden, your pan is rectangular. Ah, the circle of life. Or, rectangle of life.

So, we want the length times width, which is 9 * 5. That's 45. So, your pan is 45 square inches. Okay, now you have to deal with all your extra peppers, cucumbers, carrots and other vegetables. You had quite a harvest. You decide to can them for the winter. You keep the jars on the shelves in your apocalypse preparedness closet (you know, just in case). If a shelf can hold 6 jars from front to back and 10 jars from left to right, and you have 300 jars (I said it was a big harvest), how many shelves will you need?

So, our rectangular shelf is 6 jars wide by 10 jars long. 6 * 10 is 60, so one shelf holds 60 jars. That's our area. But wait, we have 300 jars. How many 60-jar shelves will we need for 300 jars? Just divide 300 by 60 to get 5. So, we'll need 5 shelves.

## Right Triangles

With a belly full of zucchini bread and all that canning behind us, let's talk triangles. Let's say your garden went so well you decide to branch out, so to speak, into growing and selling Christmas trees. That's ambitious of you.

You look at your remaining yard. It's 30 feet by 50 feet. So, the area of that rectangle is 30 * 50, or 1500 square feet. What if you cut it in half diagonally, like below?

Now you can grow trees in one half and still have half a yard for your annual croquet tournaments.

To unlock this lesson you must be a Study.com Member.

### Register for a free trial

Are you a student or a teacher?

#### See for yourself why 30 million people use Study.com

##### Become a Study.com member and start learning now.
Back
What teachers are saying about Study.com

### Earning College Credit

Did you know… We have over 160 college courses that prepare you to earn credit by exam that is accepted by over 1,500 colleges and universities. You can test out of the first two years of college and save thousands off your degree. Anyone can earn credit-by-exam regardless of age or education level.