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-   -   Need help calculating coordinates for a tangent point. (http://mymathforum.com/trigonometry/341481-need-help-calculating-coordinates-tangent-point.html)

 gixxerman1980 August 19th, 2017 07:17 AM

Need help calculating coordinates for a tangent point.

https://upload.wikimedia.org/wikiped...rcle-trig6.svg

So let's say I know coordinates for D (-10171.62, 490.26) angle at that point is 75.52. Also, line EF is a section of a line that starts at -10249, 0 and ends at -10094.8, 7615.2. How do I find the coordinates for A?

BTW, the angle at A is 91.16

 skeeter August 19th, 2017 07:52 AM

Quote:
 Originally Posted by gixxerman1980 (Post 578136) So let's say I know coordinates for D (-10171.62, 490.26) angle at that point is 75.52. Also, line EF is a section of a line that starts at -10249, 0 and ends at -10094.8, 7615.2. How do I find the coordinates for A? BTW, the angle at A is 91.16
Your image doesn't seem to match up with the info you provided.

Quote:
 line EF is a section of a line that starts at -10249, 0 and ends at -10094.8, 7615.2
If point E has coordinates (-10249, 0) and point F is (-10094.8, 7615.2), then point F's x-coordinate should be less than -10249. Note -10094.8 > -10249

Quote:
 BTW, the angle at A is 91.16
What angle at A? The angle at the intersection of the tangent line and radius at point A is 90 degrees.

I advise you to make a better sketch that fits your given information.

 gixxerman1980 August 19th, 2017 08:21 AM

Sorry, I found that image on google and thought it may be enough to show the point I'm trying to find coordinates for. I'll try to draw something that will be a little closer visually.

 gixxerman1980 August 19th, 2017 08:43 AM

1 Attachment(s)
Attachment 9098

I know the drawing shows the known point on the circle looking more like it is at about 50 degrees, but I hope that is close enough.

 skipjack August 19th, 2017 09:39 AM

Can you label all relevant points (A, D, E, F, etc.) and mark the known angles?

 gixxerman1980 August 19th, 2017 09:51 AM

1 Attachment(s)
Attachment 9099

 skeeter August 19th, 2017 10:20 AM

I'm not seeing the 75.52 degree angle by point D

http://mymathforum.com/attachments/t...ig_problem.jpg

 sagar233 August 19th, 2017 09:18 PM

Quote:
 Originally Posted by gixxerman1980 (Post 578178) Attachment 9099
Nothing is clear with this image.

Can you plot all the known points with origin point first, with their labels?, then try to sketch circle & angles.

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