समीकरण `cos 3x + cos x - cos 2x =0`. का व्यापक हल ज्ञात कीजिए |

Explanation

दिया है, `cos 3x + cos x - cos 2x =0`
`rArr "2 cos" (3x + x)/(2)"cos"(3x - x)/(2)- cos 2x =0`
`(because cos C + cos D = 2 " cos"(C + D)/(2)"cos"(C-D)/(2))`
`rArr " " 2 cos 2x cos x - cos 2x = 0`
`rArr " " cos 2x (2 cos x -1) = 0`
`rArr " " cos 2x = 0` या `2 cos x - 1 =0`
`rArr " " 2x = (2n +1)(pi)/(2)` या `cos x = (1)/(2)`
`rArr " " x = (2n+1)(pi)/(4)` या `cos x =(pi)/(3)`
`rArr " " x =(2n+1)(pi)/(4)` या `x=2n pi pm(pi)/(3) , (n in Z)`.