"Use the circumference formula of a circle to solve practical problems" PPT courseware on the circumference and area of ​​a circle

Description

"Use the circumference formula of a circle to solve practical problems" PPT courseware on the circumference and area of ​​a circle

teaching objectives

1. Combined with specific examples, experience the process of flexibly applying the circle circumference formula to solve practical problems.

2. Be able to flexibly use the circle circumference formula to solve simple practical problems, and be able to express ideas and methods for solving problems.

3. Understand that there are many problems related to the circumference of circles in real life, and gain successful experience in using knowledge to solve problems.

review review

1. What is the formula for the circumference of a circle?

2. What is the general value of pi?

3. Calculate the circumference of the circle.

(1)d=3cm

(2) r=8 decimeters

The circumference of a circular flower bed is 17.27 meters. What is its diameter?

Tell me, what information have you discovered?

How to find the diameter of a flower bed if its circumference is known?

method one:

Because C = πd

So diameter=17.27÷3.14 =5.5 (meter)

Answer: The diameter of the flower bed is 5.5 meters.

Method Two:

Solution: Suppose the diameter of the flower bed is x meters.

3.14x=17.27

x=17.27÷3.14

x=5.5

Answer: The diameter of the flower bed is 5.5 meters.

practice

1. The total length of the three iron hoops on a circular wooden barrel is 282.6 cm. What is the diameter of the barrel floor in centimeters?

282.6÷3÷3.14＝30 (cm)

Answer: The diameter of the floor of this barrel is 30 cm.

2. An acrobat rides a unicycle on a tightrope and can travel 31.4 meters by turning the wheel 25 times. What is the radius of the wheel?

31.4÷25÷3.14÷2＝0.2 (meter)

Answer: The radius of the wheel is 0.2 meters.

3. Wang Limin rode a bicycle across a 570-meter-long bridge. If a bicycle wheel rotates 100 times per minute, how many minutes will it take to cross the bridge? (Keep the result as an integer)

65 centimeters = 0.65 meters

570÷(3.14×0.65×100)≈3(minutes)

Answer: It takes about 3 minutes to cross the bridge.

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Update Time: 2024-10-04

This template belongs to Mathematics courseware Hebei Education Edition Sixth Grade Mathematics Volume 1 industry PPT template

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