Trig identities Flashcards
1
Q
Sin(x+y)
A
(Sin x)(cos y) + (cos x)(sin y)
2
Q
Cos(x+y)
A
(Cos x)(cos y) - (sin x)(sin y)
3
Q
Cos(x-y)
A
(Cos x)(cos y) + (sin x)(sin y)
4
Q
Sin(x-y)
A
(Sin x)(cos y) - (cos x)(sin y)
5
Q
Tan x
A
Sin x
/
Cos x
6
Q
Sec x
A
1 / cos x
7
Q
Cot x
A
Cos x
/
Sin x
8
Q
Cosec x
A
1 / sin x
9
Q
Tan(x+y)
A
Sin(x+y)
/
Cos(x+y)
10
Q
Sin(2x)
A
Sin(x+x)
= (sin x)(cos x) + (cos x)(sin x)
= 2(sin x)(cos x)
11
Q
Cos(2x)
A
Cos(x + x)
= (Cos x)(cos x) - (sin x)(sin x)
= (cos^2x) - (sin^2x)
12
Q
(Cos^2x) + (sin^2x)
A
1
13
Q
Cos^2x
A
1 - sin^2x
14
Q
Sin^2x
A
1 - cos^2x
15
Q
Cos(2x)
A
1 - 2(sin^2x)
OR
2(cos^2x) - 1
