Trig Identities Flashcards
1
Q
(Half angle) : Sin (θ/2)=
A
±√(1 - cos θ) / 2
2
Q
(Half angle) : Cos (θ/2)=
A
±√[(1 + cos θ) / 2
3
Q
(Half angle) : Tan (θ/2)=
A
±√1 - cos θ / 1 + cos θ
4
Q
(Double angle): Sin(2θ) =
A
2sinθcosθ
5
Q
(Double angle): Cos(2θ) =
A
cos2θ - sin2θ
6
Q
(Double angle): Tan(2θ) =
A
2tanθ / (1 - tan2θ).
7
Q
(Reciprocal): cscθ =
A
1/sinθ
8
Q
(Reciprocal): secθ =
A
1/cosθ
9
Q
(Reciprocal): cotθ =
A
1/tanθ
10
Q
(Quotient):
A
11
Q
(Quotient):
A
12
Q
(Pythagorean)
A
13
Q
(Pythagorean)
A
14
Q
(Pythagorean)
A
15
Q
(Sum & Difference)
A
16
Q
(Sum & Difference)
A
17
Q
(Sum & Difference)
A
