Question

sin2x = cosx

Answer 1

sin2x = 2sinxcosx
helps ?

Answer 2

so you have
2sinxcosx=cosx
2sinx=1
i guess you know how to solve it now.

Answer 3

i am realy struglling plzz help me :(

Answer 4

sinx=1/2

Answer 5

and we know
sin(30) = 1/2

so you have
sinx = sin30
so the solutions are:
x = 30 + 360k
x = 180-30+360k = 150+360k

Answer 6

tnxxx u soo much

Answer 7

than its says solve for x if e [-360;360]

Answer 8

@Coolsector, dividing both sides by \(\cos x\) removes a solution.
\[2\sin x\cos x=\cosx\\
2\sin x\cos x -\cos x=0\\
\cos x(2\sin x-1)=0\]

Answer 9

@SithsAndGiggles is right. sorry for that.

Answer 10

so we need to add the solution for
cosx = 0

Answer 11

so do you know how to solve cosx=0 ?

Answer 12

explain in detail i think i am getting it???

Answer 13

cosx(2sinx-1) = 0
gives two options
2sinx-1 = 0
which we found the solution for it
and
cosx=0
the solution for it is :
x=90+180k

Answer 14

so we have:
x=90+180k
x = 30 + 360k
x = 180-30+360k = 150+360k
were k can be 0,-+1,-+2...

Answer 15

help me solve this?