How To Find The Center Of A Circle - Method 1

http://www.AlexPleaseHelp.com

This is a quick method for finding the center of a circle. I used a program called Geogebra, but you can use pencil, paper and a compass to find the center just as easily.

This method works with any curve that is circular (ie, not parabolic or elliptical etc...). Even a portion of a circular curve works; it doesn't have to be a complete circle.

Category:

Education

Tags:

• math
• circle
• compass
• physics
• center
• homework
• science
• geometry

[mrjost55]

couldn't you just use that one line that gave you the diameter to measure it and devide by two? Instead of making another chord on the other side and having two lines intersect in the middle?

[AlexPleaseHelpDotCom]

@mrjost55 Well... yes... but the point of this sort of thing is to be able to find and draw stuff using an unmarked straight edge.

[MacGreggToo]

The Circles you draw at the END POINTS of the Cords do not need to pass thru the the opposite Point on the Cord or in other words the Circles can be any size as long as they are the SAME SIZE and bigger Circles will be more accurate.

[AlexPleaseHelpDotCom]

@MacGreggToo Yes you are correct. When I built the applet to present this construction it was just easier to make the circles pass through the opposite end points to ensure they were congruent.

[TheFurryFeline]

Thanks so much! I couldn't find a thorough enough explanation in my book so this was really helpful!

[AlexPleaseHelpDotCom]

Which book are you referring to?

[Dudeeoman]

There's a much more practical method that does not require a compass. Take the corner of a piece of paper and place it on the inside of the circle on one of its points. Mark the two other points where the paper intersects the circle. The chord connecting those points is a diameter. Repeat, and--like the video--the point of intersection of those lines is the center.

[caduser2003]

thanks



[bluetwinky]

While your method is valid, it would be nice to prove the validity of the method (as in Euclid book 3 propostion 1).

[elmdweller1]

@mrjost55 you are absolutely right. you can just pose a center perpendicular to show the center. but i came up with this at school and my geometry teacher said that it is just a derivation from pythagoras triangle rule..it is much simpler thou and I use it all the time. ( the point in space is the crossing of two lines, and only this method delivers)

[flipcubare]

THANK YOU EVER SO MUCH!! :D

[xSilkify]

Thats a triangle.

[JefafaSB]

NebraskaJimmy.... Don't stress it bro, they even have special parking spots for ya! Doesn't get much easier than that!

[russelsmithjackson]

Thanks bro

[NebraskaJimmy]

There Has Got to be something simpler than this.

[jazzGT]

sooo usefuel man.. excellent!!!

[vzarou]

how do i find in wood cercle