Trig Identities Quiz Review

Reciprocal, Quotient, Pythagorean, Sum & Difference, and Double-Angle Identities

sin(A + B)

sinAcosB + sinBcosA

sin(A - B)

sinAcosB - sinBcosA

cos(A + B)

cosAcosB - sinAsinB

cos(A - B)

cosAcosB + sinAsinB

sin2A

2sinAcosA

cos2A

cos²A - sin²A

sinθ

1/cscθ

cscθ

1/sinθ

cosθ

1/secθ

secθ

1/cosθ

tanθ

1/cotθ

cotθ

1/tanθ

tanθ

sinθ/cosθ

cotθ (quotient identity)

cosθ/sinθ

Pythagorean identities

sin²(x) + cos²(x) = 1

tan²(x) + 1 = sec²(x)

and 1 + cot²(x) = csc²(x).

Other forms of reciprocal identities

cosθsecθ = 1

sinθcscθ = 1

tanθcotθ = 1