My Math Forum Parametric?

 Geometry Geometry Math Forum

 January 13th, 2017, 03:14 AM #1 Newbie   Joined: Jan 2017 From: Somewhere Posts: 6 Thanks: 1 Parametric? Hi guys! Any good place to find lots of parametric geometry equations? (x=Whatever*t , y=Whatever*t) for example, spirals, polygons, weirder stuff... Also, how can I modify this parametric equation of a spiral so I can draw it rotated by θ degrees? x=at sin(t) y=at cos(t) Any pointers to pages with info about transformations in a 2d plane would be delightful! I've been trying to find all of this but wasn't successful, any help is appreciated! Thanks from geometry Last edited by Momonomotomo; January 13th, 2017 at 03:31 AM. Reason: Hi guys!
 January 13th, 2017, 11:12 AM #2 Senior Member     Joined: Sep 2015 From: USA Posts: 2,373 Thanks: 1276 to rotate your spiral $\theta$ degrees clockwise use $x(t) = a t \sin(t-\theta)$ $y(t) = a t \cos(t-\theta)$
 January 14th, 2017, 09:34 AM #3 Global Moderator   Joined: Dec 2006 Posts: 20,373 Thanks: 2010 That would rotate it anticlockwise by $\theta$ degrees. One needs to know whether t is in degrees.
 January 14th, 2017, 11:14 AM #4 Newbie   Joined: Jan 2017 From: Somewhere Posts: 6 Thanks: 1 Thanks for the answers! However, rotating the spiral didn't give me the intended result. You see, I want to get the path that exists between each layer of the spiral (imagine a ball going from inside out of the spiral avoiding the curves of it). I had previously plotted the spiral in an online graphic calculator. It used a polar equation, so maybe the value that gave the effect I wanted wasn't rotation, while it looked like it. That's why I was asking for info about 2d transformations, parametric equations... I've done some research and I basically need to shift the phase of the spiral. Any help? TD;DR: I need to shift the phase of the spiral to get the intersecting path of the layers Last edited by skipjack; January 14th, 2017 at 11:41 AM.
 January 14th, 2017, 11:41 AM #5 Global Moderator   Joined: Dec 2006 Posts: 20,373 Thanks: 2010 Did you try rotating it through 180°?
 January 14th, 2017, 01:54 PM #6 Newbie   Joined: Jan 2017 From: Somewhere Posts: 6 Thanks: 1 Yeah, the curves align perfectly (no matter the angle)! Not what I expected... Last edited by skipjack; January 14th, 2017 at 08:18 PM.
January 14th, 2017, 02:14 PM   #7
Senior Member

Joined: Sep 2015
From: USA

Posts: 2,373
Thanks: 1276

Quote:
 Originally Posted by Momonomotomo Yeah, the curves align perfectly (no matter the angle)! Not what I expected...
Can you post a picture of what you're after?

Last edited by skipjack; January 14th, 2017 at 08:18 PM.

 January 18th, 2017, 01:33 AM #8 Newbie   Joined: Jan 2017 From: Somewhere Posts: 6 Thanks: 1 Sorry for the delay, here's what I'm after: Apparently I'm not allowed to reply in my own topic? Maybe it's the link... Sorry for the delay, I've been trying to post this a few times this week. Last edited by skipjack; January 19th, 2017 at 12:37 AM.
 January 19th, 2017, 12:39 AM #9 Global Moderator   Joined: Dec 2006 Posts: 20,373 Thanks: 2010 I've combined your posts and changed the link to be a direct link to the image. The posts you made yesterday were awaiting approval due to the link, but I wasn't on this site at the time. Thanks from topsquark
 January 19th, 2017, 07:39 AM #10 Newbie   Joined: Jan 2017 From: Somewhere Posts: 6 Thanks: 1 Thanks, Skip!

 Tags geometry, maths, parametric, programming

 Thread Tools Display Modes Linear Mode

 Similar Threads Thread Thread Starter Forum Replies Last Post Kinroh Calculus 1 January 24th, 2015 11:50 AM jiasyuen Calculus 8 January 13th, 2015 05:07 AM james777 Calculus 1 December 10th, 2014 08:25 AM frnick Calculus 10 July 19th, 2013 11:51 AM milanstar Algebra 8 May 17th, 2012 04:23 PM

 Contact - Home - Forums - Cryptocurrency Forum - Top