SOLUTION: Find the exact values of sin(2u),cos(2u),tan(2u)using the half-angle formulas. sin u = -3/5, 0

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Question 1153915: Find the exact values of sin(2u),cos(2u),tan(2u)using the half-angle formulas.
sin u = -3/5, 0
Found 2 solutions by greenestamps, ikleyn:
Answer by greenestamps(13200)   (Show Source): You can put this solution on YOUR website!


(1) What does "sin u = -3/5, 0" mean?

(2) If you give use the values of sin u and cos u, we can't find the values of sin(2u), cos(2u), or tan(2u) using half-angle formulas -- we would need to use double-angle formulas.

If you want help with your questions, be careful to post them clearly and correctly.
Answer by ikleyn(52792)   (Show Source): You can put this solution on YOUR website!
.

(1)  First, you should not use half-angle formulas.



(2)  Second, for the given purposes, special formulas do exist in Trigonometry, that are called the double argument formulas.


     These formulas are


         

         

          = .



(3)  So, start calculating

          = +/-  = +/-  = +/-  = +/-  = +/- .


      Which sign to chose there, is the unknown fact - the problem does not provide a necessary info for it.


      In this sense, your input is FATALLY incomplete.



(4)  Having values of    and , you should substitute them into formulas for double arguments above,

     and complete the assignment in this way.

--------------------

Again, the input is FATALLY INCOMPLETE; therefore, I can not continue.

The fact that the input is incomplete, is your FAULT.

and my conclusion is that the problem is presented in the post EXTREMELY UNPROFESSIONALLY.



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