How do I solve sin 2x=-1/2sin2x=12 for 0<=x<=2pi0x2π?

1 Answer
Dec 2, 2017

x=(7pi)/12,(11pi)/12,(19pi)/12,(31pi)/12x=7π12,11π12,19π12,31π12

Explanation:

sin2x=-1/2sin2x=12

"since "sin2x<0" then x in third/fourth quadrants"since sin2x<0 then x in third/fourth quadrants

rArr2x=pi/6larrcolor(blue)"related acute angle"2x=π6related acute angle

"note "rarr0<=2x<=4pinote 02x4π

2x=(7pi)/6,(11pi)/6,(19pi)/6,(31pi)/62x=7π6,11π6,19π6,31π6

rArrx=(7pi)/12" or "(11pi)/12" or "(19pi)/12" or "(31pi)/12x=7π12 or 11π12 or 19π12 or 31π12