# Trigonometry help please?

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vestureofblood
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Trigonometry help please?

Hi gang,

I need to know how to find a particular angle without any special tools. I didn’t write down some of the angles on a light when I made them but now I need to know what they are.

How do I find what that angle is based on the measurements?

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cbrake10
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-X3-
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tan x = ((0.885-0.785)/2)/(0.090)
x = arctan(((0.885-0.785)/2)/(0.090)) = 29°

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coolperl
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Hi,

I’m not sure which angles you mean exactly, but here’s a crappy pic I made from yours:

If you are looking for ‘alpha’ then you need to calculate tangent of this angle which is 0.050/0.090=0,55555(5)
If you have this value, you go to online calc and check, what angle value corresponds to this result, and for tg=0,55555(5) the angle is 29,0546°

MRsDNF
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Does 29 degrees sound right?

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cbrake10
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The angle of the sides of the trapezoid with reference to the “body” should be 146.25 or 33.75 for the angle coolperl illustrated. Right?

edit: hurrdurr, derp, etc.; .090 corresponds to leg height not hypotenuse length….durr I feel so stoopid

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cera@1967
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Both ,X3 and coolperl are correct ! 29 degrees !

Adrian

coolperl
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cbrake10 wrote:
The angle of the sides of the trapezoid with reference to the “body” should be 146.25 or 33.75 for the angle coolperl illustrated. Right?

Nope. That would be the case, if the 0,090 value was the lenght of the diagonal part. On the picture this value is lenght of vertical projection of diagonal part.

Or in another words, your values are calculated from the sine function, but should be from tan (or tg) function, because only dimensions for tangent function are provided.

MRsDNF
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coolperl wrote:
Hi,

I’m not sure which angles you mean exactly, but here’s a crappy pic I made from yours:

If you are looking for ‘alpha’ then you need to calculate tangent of this angle which is 0.050/0.090=0,55555(5)
If you have this value, you go to online calc and check, what angle value corresponds to this result, and for tg=0,55555(5) the angle is 29,0546°

This is correct. The angle is 29 degrees.

djozz quotes, "it came with chinese lettering that is chinese to me".

"My man mousehole needs one too"

old4570 said "I'm not an expert , so don't suffer from any such technical restrictions".

Old-Lumens. Highly admired and cherished member of Budget Light Forum. 11.5.2011 - 20.12.16. RIP.

vestureofblood
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coolperl wrote:
Hi,

I’m not sure which angles you mean exactly, but here’s a crappy pic I made from yours:

If you are looking for ‘alpha’ then you need to calculate tangent of this angle which is 0.050/0.090=0,55555(5)
If you have this value, you go to online calc and check, what angle value corresponds to this result, and for tg=0,55555(5) the angle is 29,0546°

29 degrees would make sense, since that is where my compound sits by default most of the time. I think this is exactly what I needed.

So to be sure I understand. Half the distance of the change in diameter divide by the distance traveled. Then plug that number into the inverse tangent calculator and that is my angle?

So if all other things were the same but the head diameter was 1.250” I would go… 0.2325/0.090=2.5833333 For an angle of 68.83?

Also why in the equation does the decimal turn to a comma? 0.050/0.090=0,55555(5)

Thank you

In Him (Jesus Christ) was life; and the life was the light of men. And the light shineth in darkness; and the darkness comprehended it not.
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hIKARInoob
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vestureofblood wrote:
Also why in the equation does the decimal turn to a comma? 0.050/0.090=0,55555(5)

USA: 1,000 = thousand
Other countries (including your calculator): 1,000 = one point zero zero zero

So the “.” is also reversed.

hIKARInoob
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vestureofblood wrote:
So to be sure I understand. Half the distance of the change in diameter divide by the distance traveled. Then plug that number into the inverse tangent calculator and that is my angle?

Correct!

(P.S. make sure your calculator is set in “deg” instead of “rad” or “grad”)

coolperl
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vestureofblood wrote:

Also why in the equation does the decimal turn to a comma? 0.050/0.090=0,55555(5)

Thank you

Sorry, that’s a typo. Ignore it.

vestureofblood
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coolperl wrote:
vestureofblood wrote:

Also why in the equation does the decimal turn to a comma? 0.050/0.090=0,55555(5)

Thank you

Sorry, that’s a typo. Ignore it.

LOL… Shows how much I know about trig. you could have put %(*()#@)#!!)) or kldswiqeorpugjriwqfpeiofj and I would have assumed it meant something.

In Him (Jesus Christ) was life; and the life was the light of men. And the light shineth in darkness; and the darkness comprehended it not.
http://asflashlights.com/ Everyday Carry Flashlights, plus Upgrades for Maglite.