How do you solve cos^2x = 3/4?

Solve ##cos^2 x = 3/4##
Ans: ##+- pi/6## and ##+- (5pi)/6##
##cos^2 x = 3/4## –> ##cos x = +- sqrt3/2##
##a. cos x = sqrt3/2 ##–> arc ## x = +- pi/6##
##b. cos x = – sqrt3/2## –> arc ##x = +- (5pi)/6##