Question

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

Answer 1

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

Explanation:

`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!