How do you solve $sin 2x - cos x = 0$ ?

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Answer 1 · 2016-06-10T02:42:50

Use the important double angle identity $sin2x = 2sinxcosx$ to start the solving process.

$2sinxcosx - cosx = 0$

$cosx(2sinx - 1) = 0$

$cosx= 0 or sinx = 1/2$

$90˚, 270˚, 30˚ and 150˚ or pi/2, (3pi)/2, pi/6 and (5pi)/6$

This can also be stated as $pi/2 + 2pin, (3pi)/2 + 2pin, pi/6 + 2pin and (5pi)/6 + 2pin$ , n being a natural number.

Hopefully the helps!

How do you solve sin 2x - cos x = 0 sin 2x - cos x = 0?