# The distance from centre to chord

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• Oct 19th 2009, 04:36 PM
ahmads121
The distance from centre to chord
the equation of a circle with centre O(0,0) is x^2+y^2=10
the points P(1,3) and Q(-3,-1) are endpoints of chord PQ. Find the exact dictance from the centre of the cirlce ot the chord

ineed helpp!
this was hw btu our teacher never explained it
• Oct 19th 2009, 04:47 PM
mr fantastic
Quote:

Originally Posted by ahmads121
the equation of a circle with centre O(0,0) is x^2+y^2=10
the points P(1,3) and Q(-3,-1) are endpoints of chord PQ. Find the exact dictance from the centre of the cirlce ot the chord

ineed helpp!
this was hw btu our teacher never explained it

Your question cannot be answered unless you specify where from the chord you want to calculate the distance from. Do you want the perpendicular distance?
• Oct 19th 2009, 04:51 PM
ahmads121
Quote:

Originally Posted by mr fantastic
Your question cannot be answered unless you specify where from the chord you want to calculate the distance from. Do you want the perpendicular distance?

yesss the perpindicular distance!
thnxx
• Oct 19th 2009, 05:01 PM
mr fantastic
Quote:

Originally Posted by ahmads121
yesss the perpindicular distance!
thnxx

Note that by symmetry, a line drawn from the midpoint of the chord to the centre of the circle is perpendicular to the chord ....
• Oct 19th 2009, 05:05 PM
ahmads121
Quote:

Originally Posted by mr fantastic
Note that by symmetry, a line drawn from the midpoint of the chord to the centre of the circle is perpendicular to the chord ....

kaii never mind yur loosing me now confusing me
• Oct 19th 2009, 05:12 PM
mr fantastic
Quote:

Originally Posted by ahmads121
kaii never mind yur loosing me now confusing me

Do you know how to find the midpoint of a line segment drawn between two given points?

Do you know how to find the distance between two points?

Do you understand why a line from a chord to the centre of a circle is perpendicular to the chord?

If you do not understand these things then you do not have the background knowledge necessary to answer the question you posted, in which case you need to go back and review the relevant material.

Edit: All this stuff was addressed nearly two weeks ago in this thread: http://www.mathhelpforum.com/math-he...tor-chord.html. You're expected to have learned something from all the help you got there.
• Oct 20th 2009, 03:49 AM
ahmads121
Quote:

Originally Posted by mr fantastic
Do you know how to find the midpoint of a line segment drawn between two given points?

Do you know how to find the distance between two points?

Do you understand why a line from a chord to the centre of a circle is perpendicular to the chord?

If you do not understand these things then you do not have the background knowledge necessary to answer the question you posted, in which case you need to go back and review the relevant material.

Edit: All this stuff was addressed nearly two weeks ago in this thread: http://www.mathhelpforum.com/math-he...tor-chord.html. You're expected to have learned something from all the help you got there.

I can all do all that but this is a different question ineed the shortest distance
• Oct 20th 2009, 04:53 PM
mr fantastic
Quote:

Originally Posted by ahmads121
I can all do all that but this is a different question ineed the shortest distance

The shortest distance is the perpendicular distance. This is evident from symmetry.