Question

cos 5θ − cos 7θ = 0

Answer 1

solve the equation

Answer 2

cos 5x-cos7x= 0
cos(6x-x)- cos(6x+x)=0
cos 6x cos x + sin 6x sin x- cos 6x cos x + sin6x sin x = 0
2 sin 6x sin x = 0
sin 6x sin x = 0
sin 6x = 0 when 6x = (+/-) n (pi) or x = (+/-) [n (pi)]/6
sin x = 0 when x = (+/-) n (pi)

x = (+/-) [n(pi)]/6

[ -(pi), (pi)] this answer is true for this intervals in which n is between the numbers 6 and negative 6
the exact values are : (+/-) [1(pi)]/6
(+/-) [2(pi)]/6
and so forth till you reach 6