sin 2x sin x-cos x = 0 2sinx cosx sin x-cos x = 0 cosx (2(sinx)^2 -1)=0 so you have two options: 1) cos x=0 ==> x= Pi/2 or 3Pi/2 2) 2(sinx)^2 -1=0 ==> sin x = 1/sqrt(2) ==> x=PI/4 or 3Pi/4 Answer: x= Pi/2, 3Pi/2,PI/4, 3Pi/4

David :

hope this helps

David :

actually there are more: with negative

David :

3) 2(sinx)^2 -1=0 ==> sin x = -1/sqrt(2) ==> x=5PI/4 or 7Pi/4

David :

so the complete answer is this:

David :

Answer: x= Pi/2, 3Pi/2,PI/4, 3Pi/4, 5PI/4, 7Pi/4

David :

done

David :

let me know if there are any questions, it will be my pleasure to assist.

Customer:

i have different ones should i stay on this or just go to input a new question

David :

Pleas eopen a new thread and type "for david" I'l pick

David and other Pre-Calculus Specialists are ready to help you