हल कीजिए -
` cos^(2) theta - sin theta cos theta - 1/2 = 0 .`

Explanation

` cos ^(2) theta - sin theta cos theta -1/2 = 0 `
` rArr 2 cos^(2) theta - 2 sin theta cos theta -1 = 0 `
` rArr (2 cos ^(2) theta-1)=2 sin theta cos theta `
` rArr cos 2 theta = sin 2 theta `
` rArr tan 2 theta = 1 `
` rArr tan 2 theta = tan.pi/4`
` rArr 2 theta = n pi + pi/4`
` rArr theta = (npi)/2 + pi/8`