Answer:
We have sin² x + cos² x =1 for all real x.
Therefore, sin² x = 1 – cos² x = 1 – (8/17)² = 1 – 64/289 = 225/289 = (15/17)².
However, remember that if x² = a², then x can be +a or –a.
Therefore, sin x can be either –15/17 or +15/17.
Everyone but Anirban so far has forgotten the negative solution.
Explanation:
Given that sinθ=817 and cosθ<0 , we have: cosθ=−√1−sin2θ. cosθ=−√1−(817)2. cosθ=−√1−64289.