SOLUTION: Find all solutions of 16cos^2 x + 6sin x = 15. Approximate (to three significant digits), if need be. What is the answers in this? Thanks a lot.

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Question 726003: Find all solutions of 16cos^2 x + 6sin x = 15. Approximate (to three significant digits), if need be.
What is the answers in this?
Thanks a lot.
Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
16cos^2+6sinx=15
16(1-sin^2x)+6sinx-15=0
16-16sin^2x+6sinx-15=0
16sin^2x-6sinx-1=0
16sin^2x-8sinx+2sinx-1=0
8sinx(2sinx-1)+1(2sinx-1)=0
(2sinx-1)(8sinx+1)=0
sinx=1/2 OR sinx=-1/8