समीकरण ` cos 3 x+ cos x - cos 2x = 0 ` से ` theta` का व्यापक मान ज्ञात कीजिए ।

Explanation

`cos 3 x + cos x- cos 2x =0`
` rArr 2 cos 2x* cos x - cos 2x =0`
`rArr cos 2x (2 cos x-1)=0`
`rArr cos 2x = 0 "या " cos x =1/2 `
` rArr 2x = ( 2n+ 1) pi/2 " या " cos x = cos pi/3, n in I. `
` rArr 2 x = ( 2n + 1) pi/2 " या " x = 2npi pm pi/3 , n in I.`