How can i find the centre of a circle?

Answer 1

Geometrically -
draw two straight lines across the circle (not to close to where the centre approximately is, and not parallel), they will make chords. Then draw the perpendicular bisectors of the chords. The centre is where the bisectors intersect.

Algebraically -
you need an equation... get the equation into the form
(x-a)² + (y-b)² = r²
Then the centre is the point (a,b)

Hope this helps.

Answer 2

Do you mean how do you find the centre of a circle from its equation or how do you find the centre of a drawing of a circle?

If you mean from formula just put the equation into the form:
(x - h)^2 + (y - k)^2 = r^2
The centre is (h,k).

If you mean a drawing you can do the following. Draw any two straight lines through the circle(chords), don't make them parallel though. Find the centre point of each of these chords. Draw a line through the centre points you just found that are perpendicular to the chord. The point at which the two lines you just drew intersect is the centre of the circle.

Answer 3

The intersection of the perpendicular bisectors of any 2 chords of a circle will result in the centre of the circle.

Answer 4

You can find the centre of a circle by

1) Draw a horizontal line
2) Draw a vertical line such that the horizontal and the vertical line will form a cross +
3) Get a compass and draw a circle such that the pointed leg of the compass is exactly in the center of the cross +
4) After you draw the circle, you can find the centre of it, which is the point of intersection of the horizontal and vertical line.

Answer 5

Draw a line across the circle. Construct the perpendicular to this line where it touches the circle (either end). The line joining the two points where the two lines touch the circle must be a diameter (You just inscribed a right angle, and an inscribed 90 degree angle subtends a 180 degree arc -- a diameter). Repeat with another line across the circle at a different point, constructing the perpendicular. The two diameters MUST cross at the center of the circle, since all diameters go through the center of a circle.

Answer 6

Haha, are you allowed to fold the circle? Well, face it one way to you, and fold it so the bottom part of the circle touches the top part, basically, it will form a semi-circle. Run your finger along the folded part to form a crease. Unfold it and turn it so that the crease is horizontal and fold it into a semi-circle again. Unfold it. The spot where the two creases meet it the centre of the circle!

Answer 7

Make two chords and construct there perpendicular bisectors--they will intersect at the center of the circle.

Answer 8

Here is the perfect site for you. It shows you step by step how to do it including pictures. The pictures are well done so reading the instructions will not be necessary!!

Enjoy
http://www.makeitsolar.com/science-fair-ideas/90-find-circle-center.htm

Answer 9

By drawing straight lines through it and where they meet will be the centre, I think.

Answer 10

just look at the middle of the circle