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

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

RELATED QUESTIONS
using double angle formula find all values of x such 0� < x < 360� for which a) 2cos... (answered by solver91311,greenestamps)

For all values of x in the interval 0 is less than or equal to x which is less than or... (answered by lwsshak3)

Find all values of x in the interval 0 degreesis less than or equal to x wich is less... (answered by jsmallt9)

find all values of x when x is greater than or equal to 0 degrees and less than 360... (answered by solver91311)

solve for 0 (answered by stanbon)
If 0 is less than/equal to x less than/equal to 360 What are all values of x for... (answered by lwsshak3)
Find to the nearest tenth of a degree ,all values of x in the interval 0 less than/equal... (answered by Gogonati)
Find to the nearest degree all values of theta in the interval 0 degrees is less than or... (answered by stanbon)
Find all values of x such that sin 2x = sin x and 0 is less than or equal to x which is... (answered by solver91311)