btw, please ping me if you do answer
#I don't understand ASTC and how to use it with negative values.
kind pilot
inner prairie
I'm confused by the question.
kind pilot
For example, in a question like this
The answer would be whatever
cos^-1(0.5) and 360 - cos^-1(0.5)
What would we do though if it was negative?
when the functions (sin, cos or tan) are negative?
@inner prairie Do you get it now? π
inner prairie
It should be 0 <= x < 360.
kind pilot
oh sorry my bad
inner prairie
No, it's your teacher's bad.
kind pilot
oh wait in the question
kind pilot
No, it's your teacher's bad.
uhh... That is an exam from the University of Cambridge
My question isn't really about that though
I just have it as an example
inner prairie
The issue is that 0 degrees is the same angle as 360 degrees.
kind pilot
The image I posted here
That is supposdly what we use when calculate for that question
But that is assuming that the SIN/COS/TAN is positive
I know there is a different one for negatives but idk it or how to calculate it
inner prairie
But that is assuming that the SIN/COS/TAN is positive
...no, it's not "assuming" they're positive, it's saying that those are the quadrants in which they're positive.
kind pilot
sorrry yeah
It isn't assuming
But what if its negative?
What would the formulas or be or how would we calculate it?
inner prairie
...then... it's not in the quadrants in which that function is positive, is it?
Look, do you remember the unit circle definitions of sine and cosine?
kind pilot
If we have a positive, using the cos function, we would do
cos(π) for first value
and
180 + cos(π) for the 2nd value
But I re-call there being a different one for negatives
kind pilot
Look, do you remember the unit circle definitions of sine and cosine?
Yeah, radius of 1 and (cosπ, sinπ) for (x, y)
inner prairie
Yeah, radius of 1 and (cosπ, sinπ) for (x, y)
...that's not really a definition of anything.
inner prairie
...sure. So then what's cosine?
kind pilot
The adjacent side relative to an angle divided by the longest side of a triangle?
Yeah I never really understood this topic much...
I just know the calculations to an extent and when and how to use them
inner prairie
The adjacent side relative to an angle divided by the longest side of a triangle...
...the x coordinate, is the answer I was looking for.
So... when is the x coordinate negative?
inner prairie
uhh... When it's under 0...?
On the left half of the plane.
This is geometry. Visualize.
kind pilot
okay, I will
I think I get it now
Nope, I still have no idea how to do the negtatives π
inner prairie
Nope, I still have no idea how to do the negtatives π
Cosine is the x coordinate, which is negative on the left half of the plane. What angles exist on the left half of the plane?