हल कीजिए - ` cos 3 theta + 2 2 cos theta = 0`

Explanation

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