How do you solve #Cos ( x + pi/6 ) = -0.5 # over the interval 0 to 2pi?

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Answer 1 · 2016-07-14T23:59:56

#pi/2,(7pi)/6#

#cos(x+pi/6)=-1/2#

#=>cos(x+pi/6)=-cos(pi/3)#

#=>cos(x+pi/6)=cos(pi-pi/3)=cos(2/3pi)#

#=>x+pi/6=2/3pi#

#:.x=(2pi)/3-pi/6=pi/2#

Again

#=>cos(x+pi/6)=-cos(pi/3)#

#=>cos(x+pi/6)=cos(pi+pi/3)=cos(4/3pi)#

#=>x+pi/6=4/3pi#

#:.x=(4pi)/3-pi/6=(7pi)/6#