SOLUTION: using double angle formula
find all values of x such 0 degree is less than x less than 360 degree for which
a) 2cos 2x= 3-2 cos x
giv ans to 0.1
plz help its confusing
thx
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-> SOLUTION: using double angle formula
find all values of x such 0 degree is less than x less than 360 degree for which
a) 2cos 2x= 3-2 cos x
giv ans to 0.1
plz help its confusing
thx
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Question 1120455: using double angle formula
find all values of x such 0 degree is less than x less than 360 degree for which
a) 2cos 2x= 3-2 cos x
giv ans to 0.1
plz help its confusing
thx Answer by Boreal(15235) (Show Source):
You can put this solution on YOUR website! cos 2x=2cos^2 x-1
2 cos 2x=4 cos^2 x-2
therefore, 4 cos^2 x-2=3-2cos x
4 cos^2 x+2 cos x-5=0. Use quadratic formula
cos x=(1/8) (-2+/- sqrt 4+80)); sqrt (84)=9.165
cos x=(1/8)(7.165) and cos x= (1/8)(-11.165). The second is <-1 and is not possible
the first is cos x=0.895625
x= arc cos 0.895625=26.4 degrees
check
cos 52.8 deg=0.605
2 cos 43.6=1.21
3-2 cos 26.4=3-2(0.605)=1.21
26.4 degrees
