SOLUTION: How does one formally prove that : ((sin u) (csc u)) - cos^2 u = sin^2 u Thank you for your help

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Question 1192728: How does one formally prove that :
((sin u) (csc u)) - cos^2 u = sin^2 u
Thank you for your help
Answer by Theo(13342) About Me  (Show Source):
You can put this solution on YOUR website!
csc(u) = 1/sin(u)
sin(u) * csc(u) - cos^2(u) = sin^2(u) becomes:
sin(u) * 1/sin(u) - cos^2(u) = sin^2(u) which becomes:
1 - cos^2(u) = sin^2(u)
since sin^2(u) + cos^2(u) = 1, then subtract cos^2(u) from both sides of the equation to get sin^2(u) = 1 - cos^2(u)
the completes the proof.