Cos0.5 x+cos0.25 x=0

Question

Cos0.5 x+cos0.25 x=0

Answer 1

cos0.5 x+cos0.25 x=0

cos(x/2) + cos(x/4) = 0

2* cos (( x/2 - x/4)/2) * cos ((x/2 + x/4)/2) = 0

2* cos (x/8) * cos (3x/8) = 0

cos (x/8) =  0
x/8 = pi/2 + pik
x = 4pi + 8pik

cos(3x/8) = 0
3x/8 = pi/2 + pik
x = 4pi/3 + 8pik/3