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# Trig Identities

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1. I dont understand them at all
Write down the number of solutions to the equation 5sin2x=4, for 0<x<2Pie
2. With this what you can do is adjust the interval that you're looking at.

i.e to

You then have then you should be able to see how many solutions there are from looking at graphs/ CAST diagrams!
3. Nooooo im wrong its this
[QUOTE=sia_x11;65019849]0 <x <360
0 <2x <540
This tells you the 'limit'
5sinx2x=4
2x=sin^-1 × 4/5
2x=53.1301
sin is positive so is in the first and second quadrant
180-53.1301...=2x
360+53.1301...=2x
540-53.1301...=2x
Solve to find x if necassary
3 solutions
4. Sorry about that must have looked hella confusing

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