Saturday, October 28, 2017

trigonometry - Trigonometric equation cos sin and power



The problem is 2cost3sin2t+2=0.
I get to 2cost3sin2t=2
I think that I need to use a trigonometric identity like cos(x+y) and to divide 2cost3sin2t with the 22+32



Do you know how to solve this? It should be 22+32


Answer



2cost3sin2t+2=0. Write sin2t=1cos2t, then you have a quadratic equation. Solve for cost 2cost3(1cos2t)+2=03cos2t+2cost3+2=0cost=1,13.


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