Question

Ingrid claims that Cosine (negative StartFraction pi over 2 EndFraction + y) = sine (y). Review Ingrid’s steps in verifying her claim.

A 2-column table with 5 rows. Column 1 has entries Step 1, step 2, step 3, step 4, step 5. Column 2 has entries cosine (negative StartFraction pi over 2 EndFraction + y) = sine (y), cosine (negative StartFraction pi over 2 EndFraction) cosine (y) minus sine (negative StartFraction pi over 2 EndFraction) sine (y), 0 times cosine (y) minus 1 times sine (y) = sine (y), 0 minus sine (y) = sine (y), sine (y) = sine (y).

Which statement describes Ingrid’s claim that Cosine (negative StartFraction pi over 2 EndFraction + y) = sine (y) and her steps in verifying her claim?

Ingrid’s claim is correct, and her steps are correct.
Ingrid’s claim is correct, but her steps are incorrect.
Ingrid’s claim is incorrect, but her steps are correct.
Ingrid’s claim is incorrect, and her steps are incorrect.

Answer 1

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Answer:

(b) Ingrid’s claim is correct, but her steps are incorrect

Explanation:

As nearly as we can tell from the problem statement, Ingrid's table looks like the one attache. We have highlighted the incorrect steps.

Step 3 should read ...

0·cos(y) -(-1)·sin(y) = sin(y) . . . . . . . . . sin(-π/2) = -1

Step 4 should read ...

0 + sin(y) = sin(y)

So, Ingrid's conclusion is correct, but her steps are incorrect.