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41 votes
41 votes
Find sin(x) if cos(x) = -22/29

User SethMMorton
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1 Answer

7 votes
7 votes

Answer:

sin(x) = ±(√357)/29 ≈ ±0.651533

Explanation:

The relation between sine and cosine is ...

sin(x) = ±√(1 -cos(x)^2)

sin(x) = ±√(1 -(-22/29)^2) = √(1 -484/841) = √(357/841)

sin(x) = ±(√357)/29

_____

Additional comment

The sign of the cosine is negative, which places the angle in quadrant II or III. In quadrant II, the sine is positive; in quadrant III, the sine is negative. That is, we cannot tell which sign to apply from the information given.

(20, 21, 29) is a Pythagorean triple. We suspect a typo in the question: 22 is used where 20 or 21 is likely intended.

User Vladievlad
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2.4k points