![]() ![]() The distance around a circle is called the circumference. However, using computers, has been calculated to over 1 trillion digits past the decimal point. We use the Greek letter (pronounced Pi) to represent this value. If you measure the distance around a circle and divide it by the distance across the circle through the center, you will always come close to a particular value, depending upon the accuracy of your measurement. The circle to the left is called circle A since the center is at point A. This is the diameter.A circle is a shape with all points the same distance from the center. Our bike uses 20” wheels, but when we actually measure the height of the tire, it’s 24 inches, or 2 feet. We can measure the height of the tire, which is also the diameter, then use a formula to calculate the circumference. It’s not easy to measure the circumference of a tire, but we don’t need to. We count 212 “clicks.” What else do we need to know? The circumference of the tire! Then we count the number of times the sound happened as we rode around the block. How far will we travel on our BMX bicycle when we ride around the block? We do the old playing card in the spokes trick so that the card will make a sound each time it hits the fork of the bike. For instance, if we want to measure how far we travel on a bicycle, we can use the circumference of the tires to help us. This can be very useful for finding distances when using wheeled vehicles. ![]() Notice that circumference is a measure of distance. ![]() We’ll need to buy a roll of rubber edging that is more than 14.14 meters to maintain our clock. ![]() How many square meters do we need to paint, and how many meters of edging do we need to buy? The clock face needs to be removed and painted, and it needs new rubber edging all around the outside to stop water from going inside. The town hall has a giant clock that needs some maintenance. So let’s use our knowledge of these terms to solve some real-world problems. No one sells those things in quantities of pi! Exact answers will keep pi as part of the answer, but for real-world problems we use the approximate answer since it’s more useful when buying things like fencing or paint. So whenever we use 3.14, or even that pi key on a calculator, we’re using an approximation of pi and our answer will also be an approximation. That also means that it’s a decimal that goes on forever but doesn’t repeat. The reality is that pi is an irrational number, which means it can’t be written as a fraction. We sometimes use 3.14 as an approximation of pi, since that will get us close to the real answer. If we wanted to paint a large solid circle as part of a mural, we’d need to know the area of the circle to calculate how much paint we would need to buy to fill in the whole circle.įinally, we need to define pi. This is the measure of how many square units, such as square centimeters or square inches, will fit inside the circle. The big \(A\) in the formulas is the area of the circle. If we were building a circular fence around a yard, you’d need to know the circumference of the circle to know how many feet of fence to buy. It’s like the perimeter of polygons and it’s measured in length units like meters and feet. The big \(C\) in the formulas is the circumference. When we solve a problem where the diameter is known, we usually just divide the diameter by 2 to find the radius and then use the radius formulas. In practice, this area formula isn’t used as often as the radius formula, but it does work. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |