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I am getting strange results when solving this trig equation. I seem to be able to calculate 4 out 7 of the correct angles but how do i calculate the others? Maybe my method is wrong...

A = theta

2sin2A = tanA,

considering identities sin2A = 2sinAcosA and tanA = sinA/cosA

2(2sinAcosA) = sinA/cosA

4sinAcos^2A = sinA

dividing by sinA both sides

4cos^2A = 1

cos^2A = 1/4

cosA = 1/2

cosA = -1/2

A = 60

A = 300

A = 120

A = 240

missing angles 0, 180 and 360 ??

Any help would be much appreciated, thanks

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# Trigonometric equations - strange results

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