\left. \begin{array} { l } { \operatorname { cos } ^ { - 1 } ( 2 x - 1

1.	\left. \begin{array} { l } { \operatorname { cos } ^ { - 1 } ( 2 x - 1 ) = } \\ { ( A ) 2 \operatorname { cos } ^ { - 1 } x \quad ( B ) \operatorname { cos } ^ { - 1 } \sqrt { x } \quad ( C ) 2 \operatorname { cos } ^ { - 1 } \sqrt { x } \quad ( D ) N } \end{array} \right.
Answer» cos^-1(2x-1) Let x= cos^2A , or cosA=+/-x =cos^-1(2cos^2A-1) =cos^-1.cos2A =2A =2.cos^-1(x)^1/2

\left. \begin{array} { l } { \operatorname { cos } ^ { - 1 } ( 2 x - 1 ) = } \\ { ( A ) 2 \operatorname { cos } ^ { - 1 } x \quad ( B ) \operatorname { cos } ^ { - 1 } \sqrt { x } \quad ( C ) 2 \operatorname { cos } ^ { - 1 } \sqrt { x } \quad ( D ) N } \end{array} \right.

Answer»

cos^-1(2x-1)

Let x= cos^2A , or cosA=+/-x

=cos^-1(2cos^2A-1)

=cos^-1.cos2A

=2A

=2.cos^-1(x)^1/2