# How to keep the distance between two points equal when moving one, but not when moving the other?

Olympiapeter shared this question 2 years ago

I want to create a worksheet where students can experiment with the parameters of a sine function to find out what they do, specificially the parameters amplitude, phase and wavelength. I want these parameters to be modifiable by moving three points through which the sine function goes, and moving one point should change only one of the parameters. This is easy for amplitude, but not for wavelength and phase. My plan was to have point A be at a root of the function and point B at the next root. Moving point A should also move point B, so the wavelength stays constant, while the phase changes. Moving point B, however, should keep point A in place, so the phase stays constant and the wavelength changes. Is this doable without scripting? Yes it's possible without scripts, see attachment.

Note 1: A is now full free. But A=Point(xAxis) is also possible (then without offset)

Note 2: C (in version01) would not be independent from B with the command: "C=Point(PerpendicularBisector(A, B))" See correct solution in the attachment.

Note 3: variant01 with half wavelength, variant02 with full wavelength for B 1

Yes it's possible without scripts, see attachment.

Note 1: A is now full free. But A=Point(xAxis) is also possible (then without offset)

Note 2: C (in version01) would not be independent from B with the command: "C=Point(PerpendicularBisector(A, B))" See correct solution in the attachment.

Note 3: variant01 with half wavelength, variant02 with full wavelength for B 1

Note: this question was re-posted here by a spammer from https://www.reddit.com/r/ge...

I'll leave it up as it's got a great answer from rami :)