without using calculator,find all the angles in between 0' and 360' which satisfy the following trigonometric equation.
sin3x=cos(90'-2x)

Question

without using calculator,find all the angles in between 0' and 360' which satisfy the following trigonometric equation.
sin3x=cos(90'-2x)

anonymous · Answer

use the difference identity on cos (90-2x)

anonymous · Answer

difference identity?

anonymous · Answer

yeah, there's an identity for simplifying cos (a-b) to something else
but i'm too lazy to look it up today

anonymous · Answer

anonymous · Answer

is it like that?
3sinx-4sin^3  x= cos90cos2x+sin90sin2x
3sinx-4sin^3  x=sin2x
3sinx-4sin^3  x -sin 2x=0

anonymous · Answer

now use the double angle identity for sin 2x