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17-Peridot
June 13, 2013
Solved

Help! Equation Solution Request.

  • June 13, 2013
  • 30 replies
  • 13330 views

How do I "define" a semi-circle by an equation when Y is linear?

I know the cartesian formula:

x = 4 * cos ( t * 180 )

y = 4 * sin ( t * 180 )

z = 0

But I need to compensate for the trajectory (Y) which has a linear value.

I need the formula applied only to X given Y is linear 0-1.

I want to sweep a VSS to make this shape. The trajpar is the given value (t as Y):

equation_question.PNG


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Best answer by VladimirPalffy

Dear Antonius

I have tried to create SEMICIRCLE BY SWEEP feature - it is working (you can investigate my model)

Note: I have used for sweep feature the Relation (for UPPER_HALF_OF_THE_SEMICIRCLE) sd4=(r^2 - (trajpar*r)^2) ^ (1/2)

Regards,

Vladimir

30 replies

14-Alexandrite
June 14, 2013

Dear Antonius,

I think that you can combine Sweep feature with Graph feature - the values of graph will be inputs for sweep trajpar relations.

Regards,

Vladimir

17-Peridot
June 14, 2013

...or that The graph works nicely but there has to be a way to do the math.

24-Ruby IV
June 15, 2013

Hi Antonius,

Maybe "Mathcad" community able to help you: http://communities.ptc.com/community/mathcad

17-Peridot
June 18, 2013

I think the Mathcad community considers us an odd bunch and I rarely get replies... go figure

Patriot_1776
22-Sapphire II
June 18, 2013

I'd love to help, but I suck at math! I'd be graphing that baby!

17-Peridot
June 18, 2013

I think that is why we are "visual" people... Geometry is so much simpler to "grasp" - literally

Patriot_1776
22-Sapphire II
June 18, 2013

Exactly! Same result, just visual!

14-Alexandrite
June 19, 2013

Dear Antonius

I have tried to create SEMICIRCLE BY SWEEP feature - it is working (you can investigate my model)

Note: I have used for sweep feature the Relation (for UPPER_HALF_OF_THE_SEMICIRCLE) sd4=(r^2 - (trajpar*r)^2) ^ (1/2)

Regards,

Vladimir

17-Peridot
June 19, 2013

That's the one! I suspected I would have to divide it into quarters.

Here is the simplified "on the fly" version: sd4=sqrt((5^2 - (trajpar*5)^2))

And as a bonus, it covers ellipses

Thanks Vladimir!

arc_traj_eq.PNG

17-Peridot
June 19, 2013

Gopal, you didn't have to remove your reply. It is definitely worthy of this discussion:

That's the formula of a circle x^2+y^2=radius^2

with value of Y varying from with trajectory parameter.