Trigonometric Identities

Question 1

Inverse

Answer 1

ArcsinA + arccosA = pi/2
ArctanA + ArccotA = pi/2
ArcsecA + arccscA = pi/2

Question 2

Even/odd

Answer 2

Sin (-A) = -sinA
Tan(-A)= -tanA
Cos(-A) = cosA

Question 3

Half angle sine

Answer 3

Sin (A/2) = square root of (1 - cosA)/2

Question 4

Half angle cos

Answer 4

Cos(A/2) = square root of (1+cosA)/2

Question 5

Half angle tan

Answer 5

Tan (A/2) = sin A/(1 + cosA) OR (1 - cosA)/sinA

Question 6

Sine sum and difference

Answer 6

Sine keeps its sine

Sin(A+B) = sinAcosB + cosAsinB

Question 7

Cos sum and difference

Answer 7

Cos (A+B) = cosAcosB - sinAsinB

Question 8

Tan sum and difference

Answer 8

Tan(A+B) = (TanA + tan B)/(1-tanAtanB)

Question 9

Double angle sin

Answer 9

Sin(2A) = 2inAcosA

Question 10

Double angle cos

Answer 10

Cos(2A) = cos^2A - sin^2A OR 2cos^2A -1 OR 1-sin^2A

Question 11

Double angle tan

Answer 11

Tan (2A) = (2tanA)/(1-tan^2A)

Question 12

ADD SUM TO PRODUCR IDENTITIES HERE