Review the proof of the identity cos(π − A) = −cosA. cos(π − A)

Step 1: = cosπcosA − sinAsinπ

Step 2: = (−1)(cosA) + (sinA)(0)

Step 3: = −1cosA + (sinA)(0)

Step 4: = −cosA + 0

Step 5: = −cosA

At which step was an error made?

step 1
step 2
step 3
step 4

error in step 1

Step-by-step explanation:

well where is does the step not make sense?

remember cos(pi) = -1 and sin(pi)=0

that means step 1 is strange... it didn't distribute properly

it should have been:

cos(pi) - cos(A)

hope that helps! ^-^

i think its doubled. let me know

step-by-step explanation: