More trigonometric identities

lol, stats is used more for buisiness, but things like trig can be very very very helpful in mechanics / building/creating stuff.
 
first one is correct, second one isnt - you havent done a correct reciprocal (spelling?):

FrostedNipple said:
I just thought it would work because

1/sin^2θ = cosec^2θ etc etc

1/sin^2θ + 1/cos^2θ = 1/1 obviously you can't do that though.
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You can take the reciprocal of both sides, but you don't do each term individually, ie:

1 / (cos^28 + sin^28) = 1 but you can't write that as 1/cos^28 + 1/sin^28
 
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Psiko said:
The first one is fine, since cot = cos/sin = (1/sin)/(1/cos) = cosec/sec. The second one is wrong. cos^2 + sin^2 = 1, but that doesn't mean that 1/cos^2 + 1/sin^2 = 1. In fact, 1/cos^2 t + 1/sin^2 t = (cos^2 t + sin^2 t)/(cos^2 t sin^2 t) = 4cosec^2 (2t).
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Erm what ?
 
They are useful for mechanics for people asking. Although iirc this is core 3 core 4 stuff? Gonna be doing this when we go back after work shadowing. :)

It is trigonometry (triangles) but a step further than sin cos and tan.
 
Fraggr said:
They are useful for mechanics for people asking. Although iirc this is core 3 core 4 stuff? Gonna be doing this when we go back after work shadowing. :)

It is trigonometry (triangles) but a step further than sin cos and tan.
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These identities will be in C3, you'll also get extra things like harmonic form and double angles in C4.
 
Reading this actually makes me miss maths. I did maths, further maths and advanced further maths AS (or whatever it was that included P6 etc.) and now I can't even remember this kind of stuff :(
 
Given how straightforward these are, it's somewhat amusing to see some of the people struggling with them are the same people posting about how easy current A-levels are.
 
Voltar said:
So this is just for a triangle?? All that for a triangle :rolleyes:

Glad I'm an arts student :p
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Trig has applications all over the place. It's completely essential for any form of physics, engineering or pure maths.:)

But yeah, the most basic interpretation involves triangles.:p
 
don't want to derail the thread but there's not much point making a new one... doing some physics revision and i'm not quite sure how to do this..

I was wondering if anyone knows how to get T the subject in this equation:

I = Io e^-t/CR

I thought it was ln(Io/I) X CR = -t but i'm not sure if that's right?

thanks
 
Spitfir3 said:
don't want to derail the thread but there's not much point making a new one... doing some physics revision and i'm not quite sure how to do this..

I was wondering if anyone knows how to get T the subject in this equation:

I = Io e^-t/CR

I thought it was ln(Io/I) X CR = -t but i'm not sure if that's right?

thanks
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I = Io e^(-t/(RC))
I/Io = e^(-t/(RC))
ln (I/Io) = -t/RC
-RC ln (I/Io) = t
 
I'm just glad I did A-level Physics.

Symbols are useful because you don't have to write the whole numbers everytime, and can help when rearranging the equations :)
 
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