"Why are wheels made round?" Circle PPT courseware

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"Why are wheels made round?" Circle PPT courseware

Why are round wheels stable?

(1) As shown in the figure, A and B represent two points on the edge of the wheel, and O represents the axis of the wheel. What is the relationship between the distance between A and O and the distance between B and O?

(2) C represents any point on the edge of the wheel. To enable the wheel to roll smoothly, what relationship should be satisfied between the distance between C and O and the distance between A and O?

The distance from any two points on the wheel edge to the axis center is equal, and the distance from any point to the axis center is a fixed value.

definition:

The figure composed of all points on the plane whose distance from a fixed point is equal to _______ is called a circle.

The fixed point is _____, and the fixed length is the length of _____ (often called the radius). A circle with point O as the center is denoted as _____ and pronounced as _____.

Do it

Assume AB=3cm, draw a figure that meets the following requirements:

⑴The graph composed of all points whose distance to point A and point B is equal to 2cm

⑵The graph composed of all points whose distance to point A and point B is less than 2cm

Class exercises:

1. If the diagonal of square ABCD with side length 1 intersects at point O, draw a circle with A as the center and 1 as the radius. What is the relationship between points B, C, D, and O and ⊙A?

2. In the right angle △ABC, ∠C is a right angle AC=8, AB=10, the midpoint of AB is D, with point C as the center and 6 as the radius, draw ⊙C, then A, B, D and ⊙C What is the relationship?

3. Known: As shown in the figure, OA, OB and OC are the three radii of ⊙O, ∠AOC=∠BOC, M and N are the midpoints of OA and OB respectively. Verify: MC=NC．

after class homework

1. Among the following figures, the four vertices are on the same circle ( )

A. Rectangle, parallelogram B. Square, rhombus

C. Square, parallelogram D. Rectangle, isosceles trapezoid

2. Known: As shown in the figure, in the rectangle ABCD, AB=3cm, AD=4cm. If a circle is drawn with A as the center, so that at least one of the three points B, C, and D is inside the circle, and at least one point is outside the circle, find the value range of the radius r of ⊙A.

3. As shown in the figure, in the right-angled trapezoid ABCD, AD∥BC, AB⊥BC, AD=4, BC=9, AB=12, M is the midpoint of AB, draw a circle P with CD as the diameter, and judge the point M and ⊙ The positional relationship of P.

Use it once

As shown in the picture, a 6m long rope is tied to a pillar at one end and a sheep is tied to the other end. Please draw the activity area of ​​the sheep.

Improve ability:

As shown in the figure, the two right-angled sides of Rt△ABC are BC=3cm and AC=4cm. The height on the hypotenuse AB is CD. If C is the center of the circle, r1=2cm, r2=2.4cm and r3=3cm are the radii respectively. Draw a circle and try to determine the positional relationship between point D and these three circles.

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"Why are wheels made round?" Circle PPT courseware 4:

"Why are wheels made round?" Circle PPT courseware 4 Why are round wheels stable? (1) As shown in the figure, A and B represent the two points on the edge of the wheel, O represents the axis of the wheel, and the distance between A and O is What is the relationship between the distance between B and O? (2)C means on the edge of the wheel..

"Why are wheels made round?" Circle PPT courseware 3:

"Why Wheels Are Made Round" Circle PPT Courseware 3 Learning Objectives 1. Experience the process of forming the concept of a circle, and experience the process of exploring the positional relationship between points and circles. 2. Understand the concept of a circle and the positional relationship between points and circles. Why are round wheels stable? On the edge of the wheel...

"Why are wheels made round?" Circle PPT courseware 2:

"Why are wheels made round" Circle PPT Courseware 2 Learning Objective 1. Experience and perceive why wheels are made round; 2. Know the definition and representation of a circle; As shown in the figure, A and B represent two points on the edge of the wheel , point O represents the axis of the wheel, the distance between A and O..

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Update Time: 2024-12-01

This template belongs to Mathematics courseware Beijing Normal University Ninth Grade Mathematics Volume 2 industry PPT template

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