Trigonometry Flashcards
1
Q
1° =
A
Π/180 radian
2
Q
sin x = 0 ⟹ x =
A
nΠ, n is an integer
3
Q
cos x = 0 ⟹
A
x = (2n + 1) Π/2
4
Q
1 + tan^2 x =
A
sec^2 x
5
Q
1 + cot^2 x =
A
cosec^2 x
6
Q
sin(x+y)
A
sinx cosy + cosx siny
7
Q
sin(x-y)
A
sinx cosy - cosx siny
8
Q
cos(x+y)
A
cosxcosy - sinxsiny
9
Q
cos(x-y)
A
cosxcosy + sinxsiny
10
Q
tan(x+y)
A
(tanx + tany)/1-tanxtany
11
Q
tan(x-y)
A
(tanx - tany)/1+tanxtany
12
Q
cot(x+y)
A
(cotxcoty - 1)/coty + cotx
13
Q
cot(x-y)
A
(cotxcoty + 1)/coty - cotx
14
Q
cos2x
A
=cos^2 x - sin^2 x
=2cos^2 x -1
=1 - 2sin^2 x
=(1-tan^2 x)/(1+ tan^2 x)
15
Q
sin2x
A
=2sinxcosx
=(2tanx)/(1 + tan^2 x)
16
Q
tan2x
A
(2tanx)/(1-tan^2 x)
17
Q
sin3x
A
3sinx - 4sin^3 x
18
Q
cos3x
A
4cos^2 x - 3cosx
19
Q
tan3x
A
(3tanx - tan^3 x)/(1 - 3tan^2 x)
20
Q
sinC +sinD
A
2sin(C+D)/2 cos(C-D)/2
21
Q
sinC - sinD
A
2cos(C+D)/2 sin(C-D)/2
22
Q
cosC + cosD
A
2cos(C+D)/2cos(C-D)/2
23
Q
cosC - cosD
A
-2sin(C+D)/2sin(C-D)/2
24
Q
cos(Π/2 - x)
A
sinx
25
sin(Π/2 - x)
cosx
26
cos(Π - x)
-cosx
27
sin(Π - x)
sinx
28
cos(Π + x)
-cosx
29
sin(Π + x)
-sinx
30
cos(2Π - x)
cosx
31
sin(2Π - x)
-sinx
