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The number of solutions of equation 6cos...

The number of solutions of equation `6cos2theta+2cos^2(theta/2)+2sin^2theta=0, ` `-πltθltπ` is

A

3

B

4

C

5

D

6

Text Solution

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`6cos2theta+2cos^2pi/2+2sin^2pi=0`
`6cos2theta=0`
`cos2theta=0`
`2theta=(2nH)pi/2,n in Z`
`2theta=pi/2,3/2pi,5/2pi,7/2pi`
`theta=pi/4,3/4pi,5/4pi,7/4pi`.
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