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March 1st, 2017, 07:21 PM   #1
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How to calculate the 'VALUE' of a point on a circle?

The value of point A = 2 @ 0 degrees
The value of point B = 6 @ 180 degrees
How to calculate the value of point C = ? @ 120 degrees
I have a computer program that returns point C = 4.57735

Can anyone PLEASE show me this math using calculator functions?

Thank you so much for any help!
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March 2nd, 2017, 05:07 AM   #2
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You're going to have to offer a better explanation of what it is that you are trying to do, at least as far as I am concerned.
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March 2nd, 2017, 05:56 AM   #3
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Yep... we need more information to give you anything meaningful.
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March 2nd, 2017, 06:40 AM   #4
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Shouldn't it be $\displaystyle 4\frac{2}3$?
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Last edited by Xxmarijnw; March 2nd, 2017 at 06:42 AM.
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March 2nd, 2017, 08:00 AM   #5
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Thank you greg1313 and Benit13 for responding,

CIRCLE values are:
0 degrees = 0
45 degrees = 1
90 degrees = 2
180 degrees = 4
360 degrees = 8

Sorry if I misrepresented the starting point value of 2 being at 0 degrees on the circle.
What I meant was 0 degrees as my starting point which is @ 90 degrees on the circle TO 120 degrees as my ending point which is @ 210 degrees on the circle.

Trying to understand why 120 degrees doesn't equal 8 / 3 + 2.
Can anyone think of a formula as to how my computer program is calculating 4.57735 ?
I can confirm that the generated value of 4.57735 is correct in my application.
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March 2nd, 2017, 08:30 AM   #6
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What is your program for? What is it trying to work out? Is CIRCLE a subroutine? If so, can you post the source code for that specific routine here?
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March 2nd, 2017, 09:18 AM   #7
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Quote:
CIRCLE values are:
0 degrees = 0
45 degrees = 1
90 degrees = 2
180 degrees = 4
360 degrees = 8
the relationship is linear ...

$v = \dfrac{\theta}{45}$ where $v$ is the "value" (whatever that means) and $\theta$ is the angle in degrees

so, $\dfrac{120}{45} = \dfrac{8}{3}$
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March 2nd, 2017, 09:26 AM   #8
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It seems to me, from the data provided, that the "circle value" $\displaystyle C$ can be expressed as a function of the angle $\displaystyle \theta$ as follows:

$\displaystyle C(\theta)=\frac{\theta}{45^{\circ}}$

And so, as you found:

$\displaystyle C(210^{\circ})=\frac{210^{\circ}}{45^{\circ}}= \frac{14}{3}$
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March 2nd, 2017, 10:04 AM   #9
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Sorry Benit13, I don't have the source code, but here are some other values generated from the software:
45 degrees from value 2 = 3.0
90 degrees from value 2 = 4.0
120 degrees from value 2 = 4.57735
180 degrees from value 2 = 6.0
240 degrees from value 2 = 7.42265

The 45, 90 and 180 degrees makes logical sense, but not the 120 and 240.
45 = 1 + 2
90 = 2 + 2
180 = 4 + 2

There has to be a formula for the 120 and 240 calculations that I'll probably never work out.

Thank you everyone for your time and effort!
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March 2nd, 2017, 04:50 PM   #10
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Note that 4.57735... = 4 + 1/√3 and 7.42265... = 8 - 1/√3, and that tan(30°) = 1/√3.
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