Trigonometric equations and inequalities

9000046505

Level: 
C
Identify the optimal first step convenient to solve the following trigonometric equation. Do not consider the step which is possible but does not help to solve the equation. sinx=1+cosx
sin2x=1+2cosx+cos2x
sin2x=1+cos2x
substitution 1+cosx=z
sinxcosx=z

9000046507

Level: 
C
Identify the optimal first step convenient to solve the following trigonometric equation. Do not consider the step which is possible but does not help to solve the equation. 3cosx=1sinx
3cos2x=(1sinx)2
3cos2x=1sin2x
substitution 1sinx=z
substitution cosx=z

9000046508

Level: 
C
Identify the optimal first step convenient to solve the following trigonometric equation. Do not consider the step which is possible but does not help to solve the equation. 3sinx=2cosx
3sin2x=44cosx+cos2x
substitution 2cosx=z
3sin2x=4cos2x
3sin2x=12cosx+cos2x