Trigonometric identities 1: Compound angle formulae Flashcards
1
Q
sin(A + B)
A
sinA cosB + cosA sinB
2
Q
sin(A - B)
A
sinA cosB - cosA sinB
3
Q
cos(A + B)
A
cosAcosB - sinAsinB
4
Q
cos(A - B)
A
cosAcosB + sinAsinB
5
Q
tan(A + B)
A
tanA + tanB / 1-tanAtanB
remember tanθ is undefined at 90, 270, …
6
Q
tan(A - B)
A
tanA - tanB / 1 + tanAtanB
remember tanθ is undefined at 90, 270, …
7
Q
cos2A
A
cos^2 A - sin^2 A
1 - 2sin^2 A
2cos^2 A - 1
8
Q
sin2A
A
2sinAcosA
9
Q
tan2A
A
2tanA / 1- tan^2 A
where A is undefined at 45, 135, …
