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identify all solutions in the interval [0,2pi]: cos (2x) csc^2x=2cos(2x) I have no clue how to solve.

an unknown salt is either NaCN,NaC2H3O2, NaF, NaCl, or NaOCl. when 0.100 molar of the salt is dissolved in 1.00 L of solution, the ph of the solution is 8.07. what is the identity of the salt? where do I start? How do I solve it, cuz im not gettign right...

z1=[cos pi/4 +sin pi/4] z2= [cos 2pi+sin 2pi] z1= sqrt 5 solve. how do you do this? substitute z1 and do what?

thanks

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