Math question

[computerex]

Hey guys. Sorry if I sound stupid, but we haven't learnt this stuff yet in school. My question is:

Does c = a/cos(θ1)

Is there any other way to calculate the measure of c if you only have the measure of θ 1 and the measure of a?

 

[Bj]

Hey guys. Sorry if I sound stupid, but we haven't learnt this stuff yet in school. My question is:

Does c = a/cos(θ1)

Is there any other way to calculate the measure of c if you only have the measure of θ 1 and the measure of a?

Well, their is several ways;

Let A,B,C = angles
let a,b,c = sides

angle a is opposite side A (so reffering to your picture (theta)1 is angle b)

So, we can use;
sin(Opposite/Hypotenuse) = angle
cos(Adjacent/Hypotenuse) = angle
tan(Opposite/Adjacent) = angle

or use the same sin, cos, and tan as above only inversed and it will return a distance instead of angle

sin-1(Opposite/Hypotenuse) = length
cos-1(Adjacent/Hypotenuse) = length
tan-1(Opposite/Adjacent) = length

 

[computerex]

Is the way I provided correct or not? Forgive me, but I have just started 9th grade.

 

[Bj]

Does c = a/cos(θ1)

Is there any other way to calculate the measure of c if you only have the measure of θ 1 and the measure of a?

Oh, and another way to look at it;
A trigonometric figure (figure with 3 angles) has 3 angles that add to 180

so in the above diagram, you know that at least one angle is 90(degrees)
so 180-90= θ1

So now instead of, say using the sin(b/c)=θ1 you can use cos(a/c)=θ2

 

[Bj]

Is the way I provided correct or not? Forgive me, but I have just started 9th grade.

No, not quite, Its ok, everyone has to learn this at some point or another, and as you'll find out, directly relates to orbiter

ok Iam not sure if you have seen this or not...

a = angle
A = side

(a/sin(A)) = (b/sin(B)) = (c/sin(B))

so in your question you have a 90 degree angle and the angle of θ1 and (a)

so (θ1/sine(B)) = θ2/sin(A))

as of a second ago, we didnot know what θ2 was, but remember a triangle has a sum of 180 degrees for all the angles total so we take;

180-θ1-90=θ2

so;
(180-θ1-90)/(sin(A)) = distance c

does that help?

 

[computerex]

This is for an add-on that simulates dust kicking up because of the hover engines. That's why I need to be able to figure out the distance from the engines to the ground in a straight line. The easy way is to :

y offset = Altitude*-1

But this is a cheap hack, and only renders the dust completely on the ground when the hover engines are pointing straight down. It won't model the dust correctly if the hover engines were say at an angle of 60 degrees.

That's why I need to know c.

 

[computerex]

Thanks, I'll give it a try right away. BTW, are there are online tutorial sites for Trig.? I am just done with the first quarter of Geometry honors.

 

[Bj]

That's why I need to know c.

I see, well I have little programming experience so I will have no idea how you did that graphically.

I have a question though, if your only in 9th grade, you don't know trig (no offense (I mean, hey, who does know trig in 9th grade? )) but how can you know C++ or some other programming languages?

 

[Bj]

Thanks, I'll give it a try right away. BTW, are there are online tutorial sites for Trig.? I am just done with the first quarter of Geometry honors.

you can try

sos math


it looks like a good starter kit

 

[computerex]

I find programming very simple, logical algorithms are easy for me. It's the math involved in Orbiter add-ons that is my limit.

I just don't get why my way doesn't work. If:

then why can't you just use simple algebra to find c in cos (theta)1 ?

IE. c = a/cos(θ1)

 

[Bj]

I find programming very simple, logical algorithms are easy for me. It's the math involved in Orbiter add-ons that is my limit.

I just don't get why my way doesn't work. If:

then why can't you just use simple algebra to find c in cos (theta)1 ?

IE. c = a/cos(θ1)

Ahh I see, I think you are doing your algebra wrong, for the sake of simplicity lets let

A = θ1 = 45
B = θ2 = 45
C = 90
a = 5
b = 5
c = (5^2 + 5^2)^.5

on my ti 83+ it shows that
5/cos(45) = 9.5179...
and that does not = (5^2 + 5^2)^.5 = srt(50) = 7.071...

Im not sure what you are doing algebraically; but in a minute ill figure whats wrong...

 

[Bj]

:edited:

Hang on, im getting alittle mixed up as well, see I am in calculus and (doing calculus homework) with all this jumping back and forth its getting me dizzy, :lol:

 

[computerex]

Hmm. It seems it's not working, even using your way. This is what I am doing to get the offset for the y axis. The smoke trail should start at the ground.

(180-ang-90)/(sin(alt));

 

[computerex]

A = θ1 = 45
B = θ2 = 45
C = 90
a = 5
b = 5
c = (5^2 + 5^2)^.5

on my ti 83+ it shows that
5/cos(45) = 9.5179...
and that does not = (5^2 + 5^2)^.5 = srt(50) = 7.071...

Im not sure what you are doing algebraically; but in a minute ill figure whats wrong...

Well:

cos(θ1) = a/c
So simply adjust the equation to get:
a/cos(θ1)=c
or c = a/cos(θ1)

Example with simple numbers:

2 = 6/x
So you do 6/2 to get 3, which fits in the equation. Same case above...

 

[Bj]

Nice picture, and mod

but I see where I went wrong; :sorry:

a = angle
A = side

(a/sin(A)) = (b/sin(B)) = (c/sin(B))

I have these reversed, its supposed to be SIDE/sin(angle)

so (lets try this again )

c/sin(90) = b/sin(θ1)

Im having a problem with my calc, just for giggles I typed in sin of 90, it should be 1 right? but my calc says .89399???? :blink::huh:

ill figure whats wrong with this thing
:lol:

 

[Bj]

:shout:


:weird:


:suicide:

MAN, I feel like an idiot; yes your c = a/cos(θ1) works fine its this stupid calculator, well actually me, see, I had it set on radian instead of degree, and that screwed it up, so

:sorry:

sorry about all the trouble if it screwed you up or anything,
Next time ill make sure im doing it right before posting

 

[computerex]

Lol no problem. :rofl:
You just gave me a start though because I thought that I was incapable of doing even simple algebra!

 

[Bj]

Lol no problem. :rofl:
You just gave me a start though because I thought that I was incapable of doing even simple algebra!

same goes for me

 

[Bj]

Im going to download that mod right away, looks cool :speakcool:

and can you send your .cpp files with it, i want to see what you did

 

[computerex]

Im going to download that mod right away, looks cool :speakcool:

and can you send your .cpp files with it, i want to see what you did

It's not released yet. I am probably gonna do it tomorrow along with the updated version of spotlights. I always release the source code along with the add-on.