Question

Find all solutions to the equation.

7 sin2x - 14 sin x + 2 = -5

Answer 1

hint : write sin(2x)=2sinx cos x
it will be easy to solve

Answer 2

Thanks (: But, how do you find solutions? I'm not sure where to begin.

Answer 3

@amoodarya I wrote out the equation, but am stuck where to begin.

Answer 4

let's do it step by step

Answer 5

Ok (:

Answer 6

a question ?
is it sin(2x)
or sin^2(x)

Answer 7

The equation is: 7sin^2(x)-14sinx+2=-5

Answer 8

\[7\sin^2(x)-14sinx+2=-5\\7\sin^2 x-14 sinx +2+5=0\\7\sin^2 x-14 sinx +7=0\\ \div 7\\sin^2x-2sinx+1=0\\(sinx-1)^2=0\\\]

Answer 9

So, to find the solutions, I just solve for x in the equation: (sinx-1)^2=0?

Answer 10

yes . can you go on ?

Answer 11

Yes, I've got it now, thanks!! (:

Answer 12

Wait...actually. Could you explain how to find the solutions? I'm still unsure what to do about finding the solutions.

Answer 13

@amoodarya ^^ (:

Answer 14

So, would my answers be pi/2 and 3pi/2?

Answer 15

^ @amoodarya