How to determine the center of a round piece of paper

Solution] Because the center of the circle is the intersection of the two diameters of the circle, to find the center of a circle, we only need to consider the method of drawing the diameter. Here are seven ways to find the diameter, and then according to this method, find another diameter that is different from the previous one, and take their intersection point, which is the center of the circle.

Draw two strings perpendicular to each other at any point on the circle, and connect the two strings to another intersection point of the circle to obtain a diameter.

2. If a string is arbitrarily made and the perpendicular bisector of the string is made, then the perpendicular bisector of the string is a diameter.

3. At any point on the circumference of the circle, make two equal chords ab and ac (which can be truncated by a compass), and make the angular bisector of the angle bac, then the part of the angular bisector in the circle is the diameter of the circle.

Fourth, the two tangents of the circle are made by the outer point p of the circle, and the angle bisector of the angle apb is made, and the part of the angle bisector of the angle in the circle is the diameter of the circle.

5. The two tangent lines of the circle are made by the point p outside the circle, and the tangent point is a, b, the midpoint m of ab, and the part of the line in the circle is the diameter of the circle.

6. Make two strings parallel to each other, and make a straight line through the midpoint of these two strings, and the part of the line in the circle is the diameter of the circle.

7. Make two tangent lines parallel to each other, then the line connecting the two tangent points is a diameter.

The compass is used to find the specific part of the circle: first take a point A on the known circumference, take A as the center of the circle, and the appropriate length as the radius to make the circle A, and cross the known circle to two points B and C. Starting from point B, taking the length of AB as the radius, the point D is obtained by intercepting 3 times in a row on the circle A, with A and D as the center of the circle, Cd as the radius as the arc, and the two arcs intersect at E.

Then take e as the center of the circle, and the length of the EA as the radius to make the arc intersection circle a and f. The arc is made with a and b as the center of the circle and fb as the radius, and the intersection of the two arcs is the center of the known circle.

Draw two strings arbitrarily, and then make a perpendicular line of the two strings, and the intersection of the two perpendicular lines is the center of the circle.

Fold in half twice. Crease intersection.

A round piece of paper can be folded in half at least twice to get the center of the circle.

1. First of all, make a circle on the compass, as shown in the figure below.

2. Anywhere in the circle, make all lines AB.

3. Cut point 1.

4. Then pass through another place of the circle, make all lines cd, and get tangent point 2, as shown in the figure below.

5. The tangent point 1 is the perpendicular line of the tangent line, as shown in the following figure.

6. The perpendicular line of the tangent point 2 is made of another tangent, as shown in the following figure.

7. The intersection point o of the two perpendicular lines is the center of the circle. This is shown in the figure below.

A round piece of paper can be folded in half at least twice to get the center of the circle.

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A circle is a (symmetrical) figure on a flat surface, and the center of the circle can be obtained by folding a round piece of paper in half at least (twice).

A round piece of paper needs to be folded in half at least twice to find the point where the two creases intersect, the center of the circle

So the answer is: 2

Method 1: The circumferential angle of the diameter is a right angle, put the right-angle vertex of the triangular ruler on the circle, and the hypotenuse is the straight line where the diameter is located, so the center of the circle can be determined;

Method 2: Make two strings of the circle, and then make the perpendicular bisector of the two spike wheel strings, and the intersection point is the center of the circle

A round piece of paper needs to be folded in half at least twice to find the point where the two creases intersect, the center of the circle

So the answer is: twice

1.If the piece of paper is folded in half, the fold is a diameter; Fold it in half again in another position, and the intersection of the two creases is the intersection of the two diameters, that is, the center of the paper;

2.If the paper is folded in half, the crease is a diameter; Fold this diameter in half, and the midpoint of the diameter is the center of the circular piece of paper;

3.Find any three points on the paper, you may wish to set it to a, b, c, respectively, as the vertical bisector of the line segment ab, bc.

then the intersection of the bisector of the two perpendicular stools is the center of the paper;

4.Use a right-angled triangular ruler to place the right-angled vertices on the edge of the circular piece of paper, so that the other two right-angled edges and the circular piece of paper intersect at two points, and the line segment connecting the two points is the diameter; If you change the position and use the same method to find another direct annihilation path, the intersection of the two diameters is the center of the circle.

1. Fold in half twice, and the intersection of the creases is the center of the circle.

2. Draw a straight line over the circle, take the midpoint of the straight line, and make a new straight line perpendicular to the original straight line, and the midpoint of the new straight line is the center of the circle.

3. Take two strings, and the two strings are bisector perpendicular.

The intersection point is the center of the circle.

4. Take a point on the circle, and make a set of cross vertical lines through the point to divide the circle into three parts. A straight line and a circle intersect at two other points, connecting the two points. The midpoint of the coin segment is the center of the circle.

1. Make two strings of the circle, and then make the vertical bisector of these two strings, and the intersection of the two perpendicular bisectors is the center of the circle.

2. Fold the paper in half twice, and the intersection of the two broken lines is the center of the circle.

3. Put the right-angled vertex of the triangle plate on the circle, and the line segment connecting the intersection of the two right-angled sides of the triangle plate and the circle is the diameter of the circle, and use this method to make another diameter, and the intersection of the two diameters is the center of the circle.

4. Use the "hanging method" to find the center of gravity of the figure, hang the circular piece of paper with a line, draw a straight line on the circle in the direction along the line, and then draw a straight line on the other side with the same method, and the intersection of the two straight lines is the center of the circle.

Draw two intersecting strings on the piece of paper, make a vertical bisector of the two lines, and the focus is the center of the circle

Fold it in half twice, and the edges of the paper should coincide exactly. The intersection of two polylines is the center of the circle.

Fold the paper in half twice, and the intersection of the creases is the center of the circle.

1. Use a ruler to find the longest chord (that is, the diameter) of the circle, and the intersection point of the two diameters is the center of the circle.

2. If the paper can be folded in half, use the fold method to find the axis of symmetry (that is, the diameter) of the circle, and the intersection point of the two diameters is the center of the circle.

If you can only use the geometric ruler tool, then draw two strings at random, and make the perpendicular bisector of these two strings, and the intersection point of the two perpendicular bisectors is the center of the circle.