Simplify ^@\dfrac{ 1 }{ 1 + sec \theta } + \dfrac {1} { 1 - sec \theta }^@.
Answer:
^@-2 cot^2 \theta^@
- Let,
^@S = ^@ ^@\dfrac{ 1 }{ 1 + sec \theta } + \dfrac {1} { 1 - sec \theta }^@ - On adding two fractions,
^@\begin{align} & \implies S = \dfrac { (1 - sec \theta) + (1 + sec \theta) } { (1 + sec \theta)(1 - sec \theta) } \\ & \implies S = \dfrac {2} { 1 - sec^2 \theta } \end{align}^@ - Using identity: ^@sec^2 \theta - 1 = tan^2 \theta,^@
^@\begin{align} & \implies S = \dfrac {2} { (-tan^2 \theta) } \\ & \implies S = -2 cot^2 \theta \end{align}^@