Question

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

Answer 1

Answer:

Step - 2

Step-by-step explanation:

Given identity is,

$\text{sin}(A-\frac{3\pi }{2})=\text{cosA}$

We will take the left hand side of the equation and prove it equal to the right hand side of the equation.

$\text{sin}(A-\frac{3\pi }{2})=\text{sinA}\text{cos}(\frac{3\pi }{2})}-\text{sin}(\frac{3\pi}{2})\text{cosA}$ [Step - 1]

                  = sinA(0) - cosA(-1) [Step - 2]

                  = sinA(0) + (1)cosA [Step - 3]

                  = 0 + cos A [Step - 4]

                  = cosA [Step - 5]

There is an error in Step - 2 .

It should be sinA(0) - cosA(-1) in place of sinA(0) + cosA(-1).                

                   

Answer 2

Answer:

Step 2

Step-by-step explanation:

completed test on edge