Trig Identities Flashcards
1
Q
sin x ≈
A
x
2
Q
cos x ≈
A
1 - 0.5x^2
3
Q
Differentiate sinx
A
cosx
4
Q
Differentiate cosx
A
-sinx
5
Q
differentiate tanx
A
sec^2x
6
Q
Differentiate cosecx
A
-cosecxcotx
7
Q
Differentiate secx
A
tanxsecx
8
Q
Differentiate cotx
A
-cosec^2x
9
Q
How to use Rsin(x+α)
A
Expand to
Rsinxcosα + Rsinαcosx
Then comepare coefficients
- square and add
- divide, sinx/cosx = tanx to solve
10
Q
Sin2A
A
= 2sinAcosA
11
Q
Cos2A =
A
cos^2A - sin^2A
(Or sub in sin^2A+cos^2A = 1)
12
Q
Tan2A
A
= 2tanA / (1-tan^2A)
13
Q
sin(A+B) =
A
sinAcosB+sinBcosA
14
Q
cos(A+B) =
A
cosAcosB - sinAsinB
15
Q
tan(A+B)
A
tanA+tanB / (1-tanAtanB)
