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GoplerGop
Newbie
Joined: 19.Sep.2013
Location: United States
Using: AutoCad2012
Status: Offline
Points: 16
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Topic: Picture 34 Posted: 08.Oct.2013 at 19:17 |
if anyone knoows, please help me with a hint. thx so much
I know how to get the circle and polygon but i can never get to the arc shape A and B.
please help, thx so much
gary
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John Connor
Senior Member
Joined: 01.Feb.2011
Location: United States
Using: AutoCAD 2018
Status: Offline
Points: 7175
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Posted: 08.Oct.2013 at 19:57 |
You are required to calculate the radii of the two missing arcs from the information provided?
Well the arcs appear to be tangent to the inner circle but they are not tangent to the outer circle or the sides of the polygon.
Regarding the two crosses < + > I assume they represent the center of the arcs. Are the supposed to be equidistant from the nearest corner of the polygon?
Edited by John Connor - 08.Oct.2013 at 20:13
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"Humans have a strength that cannot be measured. This is John Connor. If you are reading this, you are the resistance."
<<AutoCAD 2015>>
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John Connor
Senior Member
Joined: 01.Feb.2011
Location: United States
Using: AutoCAD 2018
Status: Offline
Points: 7175
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Posted: 08.Oct.2013 at 20:17 |
I faked it.
Edited by John Connor - 08.Oct.2013 at 20:19
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"Humans have a strength that cannot be measured. This is John Connor. If you are reading this, you are the resistance."
<<AutoCAD 2015>>
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John Connor
Senior Member
Joined: 01.Feb.2011
Location: United States
Using: AutoCAD 2018
Status: Offline
Points: 7175
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Posted: 10.Oct.2013 at 11:47 |
Hey Gopler what happened? You didn't give up on this already did you?
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"Humans have a strength that cannot be measured. This is John Connor. If you are reading this, you are the resistance."
<<AutoCAD 2015>>
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GoplerGop
Newbie
Joined: 19.Sep.2013
Location: United States
Using: AutoCad2012
Status: Offline
Points: 16
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Posted: 12.Oct.2013 at 16:14 |
lol, John, thx for reminding me, i am stil working on it, i am feeling it, it''s suppose to come.....
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John Connor
Senior Member
Joined: 01.Feb.2011
Location: United States
Using: AutoCAD 2018
Status: Offline
Points: 7175
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Posted: 13.Oct.2013 at 13:17 |
You're still working on it? I would think that by now you would have come up with something. Post an image of what you have accomplished so far.
I guess there was no further dimensional information available?
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"Humans have a strength that cannot be measured. This is John Connor. If you are reading this, you are the resistance."
<<AutoCAD 2015>>
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GoplerGop
Newbie
Joined: 19.Sep.2013
Location: United States
Using: AutoCad2012
Status: Offline
Points: 16
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Posted: 14.Oct.2013 at 06:16 |
yeah, i got the questions straight from my textbook. My teacher he said he would let me know later on without date.
My work so far: The huge circle and six polygon.
I tried several with, arc, circle, which is all i know of, none of them seems really work.
I will just keep annoying my teacher till he reveals the know how.
thx for asking JOhn, love your spirit.
Gary
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John Connor
Senior Member
Joined: 01.Feb.2011
Location: United States
Using: AutoCAD 2018
Status: Offline
Points: 7175
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Posted: 14.Oct.2013 at 12:43 |
My "spirit" is the result of drinking too much coffee.
I used the trial-and-error (no math) approach which took me three tries.
I'm wondering if a three point spline might get one started on a visually acceptable solution. Since I am not on my CAD computer at the moment I can't say for sure.
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"Humans have a strength that cannot be measured. This is John Connor. If you are reading this, you are the resistance."
<<AutoCAD 2015>>
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John Connor
Senior Member
Joined: 01.Feb.2011
Location: United States
Using: AutoCAD 2018
Status: Offline
Points: 7175
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Posted: 15.Oct.2013 at 14:30 |
I tried the spline idea but it did not work. So, how are the radii being calculated?
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"Humans have a strength that cannot be measured. This is John Connor. If you are reading this, you are the resistance."
<<AutoCAD 2015>>
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Kent Cooper
Senior Member
Joined: 12.Mar.2013
Location: United States
Using: AutoCAD2020, 2023
Status: Offline
Points: 629
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Posted: 16.Oct.2013 at 15:35 |
In Picture 34, it doesn't quite look to me as though the star-arm Arcs are tangent to the inner 25-unit-diameter Circle, but nothing else seems very likely, so I assume that's what's intended. If so, the attached drawing shows what would need to be calculated to determine their center points.
You would need to find the place at which a location on the hexagon (blue), or an extension of one of its edges, is the same distance from a corner of the hexagon and from one side or the other of the inner Circle. The series of green and red Points represent the path of the intersection of the green and red arcs as they change size with their distances from those references equal. For both the green and red, one of the arc radii is measured from the corner of the hexagon that the star-arm Arcs must meet. In the case of the green arcs, the other radius is measured through the center of the inner Circle to the far side of it; in the case of the red, it's from the near side of it.
Where those paths of Points intersect the hexagon or its extension determines the center points of the star-arm Arcs. Those series of Points are not linear (I filled in the whole path with the green ones to make that obvious), but I'm not sure whether that would be a hyperbolic curve, or perhaps parabolic or elliptical, or none of those. I drew Splines along a series of them in the area of intersection, and used the intersections of the Splines with the hexagon and its extension as the centers for the Arcs, with their radii defined at the corner of the hexagon. The green layout elements determine the cyan Arc, and the red elements determine the yellow Arc. Because the Splines don't precisely represent the correct path of the Points, the results are not completely precise -- the yellow Arc intersects the inner Circle twice very close together, and the cyan Arc doesn't quite intersect it.
I doubt that AutoLISP's mathematical functions would be capable of calculating the precise positions of those center points. You would need to come up with equations defining the paths of Points (the hard part), and for an edge of the hexagon (easy enough), and solve for their intersection. Maybe that's possible, but it's beyond my capabilities. It could be done with a routine by trial and error, refining the determination until some defined level of precision is achieved, but I doubt it can be done with absolute accuracy.
Edited by Kent Cooper - 16.Oct.2013 at 22:11
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