Summary of Trig Identities (1 Viewer)

[Demise]

Continuously throughout the year I fall down on these. Could someone please give me a summary of trig identities?

I know:

Sin x / cos x = tan x
Cos x / sin x = cot x
1 / sin x = cosec x
1 / cos x = sec x
1 / tan x = cot x

I also know that:
(sin x)^2 + (cos x)^2 = 1

But what else?

 

[ProtoStar]

From (sin x)^2 + (cos x)^2 = 1
we also get (cosecx)^2 -1 = (cotx)^2
and (tanx)^2 +1 =(secx)^2

 

[Demise]

From (sin x)^2 + (cos x)^2 = 1
we also get (cosecx)^2 -1 = (cotx)^2
and (tanx)^2 +1 =(secx)^2

Sweet, thank you.

There's also some that are like sin x - 1 = cos x and cos x + 1 = sin x
Are they real or is that false?

 

[kfnmpah]

look download an app on your phone called math formulary it has all the things

/i do maths at uni run at me you silly school children

 

[HSC2014]

Sweet, thank you.

There's also some that are like sin x - 1 = cos x and cos x + 1 = sin x
Are they real or is that false?

You're probably thinking of rearranging sin^2x + cos^2x = 1
to sin^2x = 1 - cos^2x
and cos^2x = 1 - sin^2x

 

[Demise]

You're probably thinking of rearranging sin^2x + cos^2x = 1
to sin^2x = 1 - cos^2x
and cos^2x = 1 - sin^2x

Ahh sweet, thank you.

 

[Demise]

look download an app on your phone called math formulary it has all the things

/i do maths at uni run at me you silly school children

Haha that app is bad-ass, thank you! <3