Math Is Fun Forum

model

Member

Registered: 2011-08-10

Posts: 142

find the other point on the circle with center point and radius of cir

Hy ,

if we have radius of a circle and center value .
then how can we find the other point on the circle ?

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bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: find the other point on the circle with center point and radius of cir

Hi model;

Any point on the circumference?

Choose an x and just plug into

or choose a y and plug into

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In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Bob

Administrator

Registered: 2010-06-20

Posts: 10,649

Re: find the other point on the circle with center point and radius of cir

hi model

If the radius is 'r' and the centre is at (a,b) then the x and y co-ordinates for points on the circumference are connected by the equation:

So you can re-arrange this to make 'y' the subject:

So you may choose a value for x and compute the corresponding two values for y.

Of course not all values of x will generate valid 'y's as you may end up with the square root of a negative number.

Bob

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Children are not defined by school ...........The Fonz
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