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• ⓐ$\displaystyle \frac{d} {dx} \sec ^ {-1} x= \frac{1} {x {\sqrt {x^2 +1}}}$
• ⓑ$\sin ^ {-1} x+ \cos ^ {-1} x = \pi$
• ⓒ$\displaystyle \tan ^ {-1} \left (\frac{1} {2} \right) + \tan ^ {-1} \left (- \frac{1} {3} \right) = \tan ^ {-1} \left (\frac{1} {6} \right)$
• ⓓ$\displaystyle \lim _ {h \rightarrow 0} {\frac{\sinh ^ {-1} h} {h} =0}$