1
cos2x+sin2x
1
2
acosx+bsinx
√(a2+b2)cos(x-arctan(b/a))
3
cosxcosy+sinxsiny
cos(x+y)
4
cosxcosy+sinxsiny
cos(x-y)
5
cos1/2x
±√[1/2(1+cosx)]
6
2cos2x-1
cos2x
7
cos2x-sin2x
cos2x
8
1-2sin2x
cos2x
9
cot(90º-x)
tanx
10
cosx/sinx
cotx
11
cot2x+1
csc2x
12
csc(-x)
-cscx
13
sec(-x)
sec x
14
sin 1/2 x
±√[1/2(1-cosx)]
15
2sinxcosx
sin2x
16
tan(90º-x)
cot
17
(1-cosx)/sinx
tan1/2x
18
sinx/cosx
tanx
19
(2tanx)/(1-tan2x)
tan2x
20
tan2x+1
sec2x
21
cos(x− y)
cos x cos y + sin x sin y
22
cos(x+ y)
cosxcos y-sin x sin y