"Perfect Graphics" PPT Courseware 5

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"Perfect Graphics" PPT Courseware 5

A circle is a curved figure on a plane.

This point in the center of the circle is called the center of the circle.

The line segment connecting the center of a circle to any point on the circle is called the radius.

The line segment that passes through the center of a circle and has both ends on the circle is called the diameter.

Use the round piece of paper in your hand to draw, measure, fold and explore

1. How many radii and how many diameters can be drawn in the same circle? How did you discover it?

2. In the same circle, are the lengths of the radii the same? What about diameter? How did you discover it?

3. What is the relationship between the diameter and radius of the same circle? How did you discover it?

4. Is a circle a symmetrical figure? How many axes of symmetry does it have? How did you discover it?

Choose one

Which of the following sentences is correct ( )

A. All radii are equal in length.

B. All diameters are equal in length.

C. The diameter is twice the radius, and the radius length is half the diameter length.

D. In the same circle, the lengths of all radii are equal, the lengths of all diameters are equal, and the diameter length is twice the radius length.

How to draw a circle: determine the radius, determine the center, and rotate once

1. Separate the two legs of the compass and determine the distance (i.e. radius) between the two legs.

2. Fix one foot with the needle tip at one point (i.e., the center of the circle).

3. Rotate one foot with the pencil tip in one circle to draw a circle.

Trial questions

1. Use a compass to draw a circle with a radius of 2 cm, and mark its center, radius, and diameter with the letters O, r, and d respectively.

2. Draw a circle with a diameter of 4 cm.

discuss:

1. Why are the wheels designed to be round?

2. If the wheels were made into square or oval shapes, how would we feel when we sat on them?

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"Perfect Graphics" PPT courseware 4:

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"Perfect Graphics" PPT courseware 3:

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"Perfect Graphics" PPT courseware 2:

"Perfect Shape" PPT Courseware 2 Understanding Circles (1) Find a way to draw a circle on paper. A circle is a curved figure on a plane. (2) Tell me how you drew the circle? Compare the plane straight line figures you have learned before with the ones you just drew...

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Update Time: 2024-07-01

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

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