If `cos theta=-1/2` and `0^@ < theta < 360^@` then the solutions are `a. 60^@, 240^@, b.120^@, 240^@, c.120^@, 210^@, d.120^@, 300^@`

Explanation

Given: `cos theta=−1/2`


`costheta=−cos60^∘`


Since,` costheta<`0 in second and third quadrants, and


`cos(180^∘−theta)=cos(180^∘+theta)=−costheta`


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