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#1 2012-11-10 21:52:00
- danthemaths
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Geometry Question - Please Help
I have a question saying "Hence find the coordinates of the point C such that AC is a diameter of this circle".
I already know:
Points: A(0,2) B(4,-2)
Equation of line AB: x^2+y^2-2x+2y=8 => and simplify that you get: (x-1)^2+(y+1)^2=10
Perpendicular Equation to line AB (through B): y=-x+2
I do not know how to work this out! Could you please explain to me step by step if u can on how to solve this?
Thanks in advance
Dan
#2 2012-11-10 22:23:01
- bob bundy
- Moderator
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Re: Geometry Question - Please Help
hi Dan,
Welcome to the forum.
How much was given in this question?
Just points A and B is not enough to fix one circle, so I'll assume you were told the equation as well.
So (1,-1) is the centre of the circle. Let's call it O.
Then from A to O is the same as from O to C. (as you want AOC to be a straight line and diameter.)
That's enough to just count across and down from A to O and hence find C without needing perpendicular lines.
Bob
You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei
#3 2012-11-10 22:33:26
- bobbym
- Administrator
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Re: Geometry Question - Please Help
Hi danthemaths;
First you should always have a drawing to help you think about the question and also to pose it for others.
Perpendicular Equation to line AB (through B): y=-x+2
Although it does not matter I am not getting that equation for the perpendicular.
In mathematics, you don't understand things. You just get used to them.
Probability is the most important concept in modern science, especially as nobody has the slightest notion what it means.
90% of mathematicians do not understand 90% of currently published mathematics.