` cos 3 theta + cos theta = 0` को हल कीजिए ।

Explanation

` cos 3 theta + - cos theta = 0 `
` rArr cos 3 theta = - cos theta = cos (pi-theta)`
` rArr 3 theta = 2 n pi pm (pi - theta) `
` rArr 3 theta = 2 n pi pm (pi - theta) `
` rArr 4 theta = 2 n pi " या " 2 theta = 2 n pi - pi `
` rArr 4 theta = ( 2 n + 1) pi "या " 2 theta = ( 2n-1) pi `
` rArr 4 theta = ( 2 n +1) pi "या" 2 theta = (2n - 1) pi `
` rArr theta = ( 2n +1) .pi/4 " या " theta = ( 2n - 1) . pi/2 `
` rArr theta = (2n +1) pi/4 "या " theta = (2n -1) pi/2 `