\left. \begin{array} { l } { \text { Prove that:- } \frac { \operatorname { cos } 5 x + \operatorname { cos } 4 x } { 1 - 2 \operatorname { cos } 3 x } = - \operatorname { cos } 2 x - \operatorname { cos } x } \\ { \text { Solve:- } \operatorname { cos } ^ { 2 } x - \operatorname { sin } x - \frac { 1 } { 4 } = 0 } \end{array} \right.

\left. \begin{array} { l } { \text { Prove that:- } \frac { \operatorn

1.	\left. \begin{array} { l } { \text { Prove that:- } \frac { \operatorname { cos } 5 x + \operatorname { cos } 4 x } { 1 - 2 \operatorname { cos } 3 x } = - \operatorname { cos } 2 x - \operatorname { cos } x } \\ { \text { Solve:- } \operatorname { cos } ^ { 2 } x - \operatorname { sin } x - \frac { 1 } { 4 } = 0 } \end{array} \right.
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