 My Math Forum Problem involving a unit circle and two other coordinates
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 April 3rd, 2019, 01:07 AM #1 Newbie   Joined: Apr 2019 From: South Africa Posts: 7 Thanks: 0 Problem involving a unit circle and two other coordinates I have a little problem that I hope the community would be able to assist me with. I have a unit circle and inside that unit circle I have a point (A), outside that unit circle I have another point (B). Is there a way to find the coordinates of the point that intersects the radius of the unit circle and the line AB ? Am I making the problem clear enough ? April 3rd, 2019, 01:27 AM #2 Senior Member   Joined: Feb 2016 From: Australia Posts: 1,838 Thanks: 653 Math Focus: Yet to find out. If by intersects the radius you mean intersects the circle, then yes, you have all the information you need. April 3rd, 2019, 02:31 AM #3 Newbie   Joined: Apr 2019 From: South Africa Posts: 7 Thanks: 0 Awesome any ideas as to any online resources that I can use to figure it out ? I am not a school student and need to figure this out for a little "Project" Thanks... April 3rd, 2019, 04:31 AM #4 Newbie   Joined: Apr 2019 From: South Africa Posts: 7 Thanks: 0 My math skills are not very good and I would really appreciate the assistance, how would I even google such a problem ? Thanks  April 3rd, 2019, 05:31 AM   #5
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Quote:
 Originally Posted by R4tt3xx I have a little problem that I hope the community would be able to assist me with. I have a unit circle and inside that unit circle I have a point (A), outside that unit circle I have another point (B). Is there a way to find the coordinates of the point that intersects the radius of the unit circle and the line AB ? Am I making the problem clear enough ?
Understand there are an infinite number of radii in a circle. Every point between point A inside the circle and the point on the unit circle where AB intersects the circle is a point on one of those many radii. April 3rd, 2019, 06:00 AM #6 Newbie   Joined: Apr 2019 From: South Africa Posts: 7 Thanks: 0 Let me rephrase what I want to do.. I have a circle and a line starting in the circle, radius 1, which ends outside the circle. I want to know what formulas I would use to determine the x and y coordinate of intersection point between circle radius 1 and the line. For example. Point A and the center of my circle, coordinate 0,0 are both the same. Point B is 2 units away at coordinate 0,2. 0,1 is my intersection point. Thankyou for your time.. April 3rd, 2019, 06:06 AM   #7
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Quote:
 Originally Posted by R4tt3xx Point A and the center of my circle, coordinate 0,0 are both the same. Point B is 2 units away at coordinate 0,2. 0,1 is my intersection point.
The radius of such a circle is concurrent to AB so there are an infinite number of intersection points.

Perhaps it's not clear to me exactly what you mean. April 3rd, 2019, 06:24 AM #8 Newbie   Joined: Apr 2019 From: South Africa Posts: 7 Thanks: 0 Ok allow me to rephrase then... I am only interested in the outer most edge of the circle where the radius is 1 April 3rd, 2019, 06:37 AM #9 Math Team   Joined: Jul 2011 From: Texas Posts: 3,018 Thanks: 1604 Since A is at the origin and the unit circle is also,then the point of intersection for that segment AB and the circle would be $(x,y) = (\cos{\theta},\sin{\theta})$ where $\cos{\theta} = \dfrac{x_B}{\sqrt{x_B^2 + y_B^2}}$ and $\sin{\theta} = \dfrac{y_B}{\sqrt{x_B^2 + y_B^2}}$ April 3rd, 2019, 12:18 PM #10 Newbie   Joined: Apr 2019 From: South Africa Posts: 7 Thanks: 0 What if A was at any location within the circle of radius 1 ? Sorry for asking another question... Tags circle, coordinates, involving, problem, unit Thread Tools Show Printable Version Email this Page Display Modes Linear Mode Switch to Hybrid Mode Switch to Threaded Mode Similar Threads Thread Thread Starter Forum Replies Last Post Volle Physics 2 July 5th, 2016 12:52 PM doryyroryy Pre-Calculus 1 November 15th, 2014 04:18 AM Aiyla Algebra 1 February 14th, 2012 12:48 AM brunojo Algebra 0 March 20th, 2009 04:50 PM Nate Algebra 1 December 25th, 2008 02:16 PM

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