A mistake made by Zhiming

Using R formular

Trigonmetry Formular O LeveL A Maths That are given

This are the formulars given in Further Trigonmetry

sin²x+cos²x=1

sin(A+B) = sinAcosB+ cosAsinB

sin(A-B) = sinAcosB - cosAsinB

cos(A+B) = cosAcosB-sinAsinB

cos(A-B) = cosAcosB+sinAsinB

tan(A+B) = [tanA+tanB)]/(1-tanAtanB)

tan(A-B) = [tanA-tanB)]/(1+tanAtanB)

sin2A=2sinAcosA

cos2A=cos²A-sin²A

cos2A=2cos²A-1

cos2A=1-2sin²A

tan2A=Tan2A/(1+tan²A)

sinA+sinB=2sin[(A+B)/2]cos[(A-B)/2]

sinA-sinB= 2cos [(A+B)/2] sin [(A-B)/2]

cosA+cosB=2 cos [(A+B)/2]cos[(A-B)/2]

cosA-cosB=-2sin[(A+B)/2] sin [(A-B)/2]

Formulars That are Not given

a cos θ ± b sin θ = R cos (θ ∓ α)

a sin θ ± b cos θ = R sin (θ ± α)

where

and a > 0, b > 0, α is acute