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)
