Trig Identities Flashcards
1
Q
Sin θ =
A
1/Csc θ
2
Q
Cos θ =
A
1/Sec θ
3
Q
Cot θ =
A
1/Tan θ
4
Q
1+tan2 a =
A
sec2 a
5
Q
cosec2 a =
A
1 + cot2 a
6
Q
Sin (-θ) =
A
– Sin θ
7
Q
Cos (-θ) =
A
Cosθ
8
Q
Tan (-θ) =
A
– Tan θ
9
Q
Cot (-θ) =
A
– Cot θ
10
Q
Sec (-θ) =
A
Sec θ
11
Q
Csc (-θ) =
A
-Csc θ
12
Q
sin (180°- θ) =
A
sinθ
13
Q
cos (180°- θ) =
A
-cos θ
14
Q
cosec (180°- θ) =
A
cosec θ
15
Q
sec (180°- θ)=
A
-sec θ
16
Q
tan (180°- θ) =
A
-tan θ
17
Q
cot (180°- θ) =
A
-cot θ
18
Q
sin (θ/2) =
A
±√[(1 – cosθ)/2]
19
Q
cos (θ/2) =
A
±√(1 + cosθ)/2
20
Q
tan (θ/2) =
A
±√[(1 – cosθ)(1 + cosθ)]
21
Q
Sin A + Sin B =
A
2 Sin(A+B)/2 . Cos(A-B)/2
22
Q
Cos A + Cos B =
A
2 Cos(A+B)/2 . Cos(A-B)/2
23
Q
Sin A – Sin B =
A
2 Cos(A+B)/2 . Sin(A-B)/2
24
Q
Cos A – Cos B =
A
-2 Sin(A+B)/2 . Sin(A-B)/2
25
Sin A. Sin B =
[Cos (A – B) – Cos (A + B)]/2
26
Sin A. Cos B =
[Sin (A + B) – Sin (A – B)]/2
27
Cos A. Cos B =
[Cos (A + B) – Cos (A – B)]/2
