- #1

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## Homework Statement

Evaluate cos(θ + π/2) if sin θ = 3/7, exactly.

## Homework Equations

How do I go about doing this exactly instead of approximately on the calculator?

## The Attempt at a Solution

The only way I know how to do it is taking the inverse sin of 3/7 and adding 90 degrees and taking the cos of that result.

Thank you for your time!