Trig Identities Flashcards
1
Q
Cos(α-β)
A
CosαCosβ + SinαSinβ
2
Q
Cos(α+β)
A
CosαCosβ - SinαSinβ
3
Q
Sin(α-β)
A
SinαCosβ - CosαSinβ
4
Q
Sin(α+β)
A
SinαCosβ + CosαSinβ
5
Q
Tan(α+β)
A
Tanα + Tanβ/1-TanαTanβ
6
Q
Tan(α-β)
A
Tanα - Tanβ/1+TanαTanβ
7
Q
Sin2α
A
2SinαCosα
8
Q
Cos2α
A
Cos^2α - Sin^2α = 2 Cos^2α - 1 = 1 - 2 Sin^2α
9
Q
Sin^2α
A
1 - cos2α/2
10
Q
Cos^2α
A
1 + Cos2α/2
11
Q
Sin(α/2)
A
±√1-Cosα/2
11
Q
Cos(α/2)
A
±√1+Cosα/2
12
Q
SinαCosβ
A
1/2 [Sin(α+β) + Sin(α-β)]
13
Q
CosαSinβ
A
1/2 [Sin(α+β) - Sin(α-β)]
14
Q
CosαCosβ
A
1/2 [Cos(α+β) + Cos(α-β)]
15
Q
SinαSinβ
A
1/2 [Cos(α-β) - Cos(α+β)]
16
Q
Sinα + Sinβ
A
2 Sin(α+β/2) Cos (α-β/2)
17
Q
Sinα - Sinβ
A
2 Cos(α+β/2) Sin(α-β/2)
18
Q
Cosα + Cosβ
A
2 Cos(α+β/2) Cos(α-β/2)
19
Q
Cosα - Cosβ
A
-2 Sin(α+β/2) Sin(α-β/2)
