Review the steps of the proof of the identity Sine (A minus StartFraction 3 pi Over 2 EndFraction) = cosine A. Sine (A minus StartFraction 3 pi Over 2 EndFraction)

Step 1: = Sine A cosine (StartFraction 3 pi Over 2 EndFraction) minus cosine A sine (StartFraction 3 pi Over 2 EndFraction)

Step 2: = (Sine A) (0) + cosine A (negative 1)

Step 3: = (Sine A) (0) + (1) (cosine A)

Step 4: = 0 + cosine A

Step 5: Cosine A

At which step was an error made?

step 1
step 2
step 3
step 4