Prove the following identities, where the angles involved are acute angles for which the expressions are defined.

$\frac{\cos A}{1+\sin A}+\frac{1+\sin A}{\cos A}=2 \sec A$

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$\frac{\cos A}{1+\sin A}+\frac{1+\sin A}{\cos A}=2 \sec A$

$L.H.S.\,=\frac{\cos A}{1+\sin A}+\frac{1+\sin A}{\cos A}$

$=\frac{\cos ^{2} A+(1+\sin A)^{2}}{(1+\sin A)(\cos A)}$

$=\frac{\cos ^{2} A+1+\sin ^{2} A+2 \sin A}{(1+\sin A)(\cos A)}$

$=\frac{\sin ^{2} A+\cos ^{2} A+1+2 \sin A}{(1+\sin A)(\cos A)}$

$=\frac{1+1+2 \sin A}{(1+\sin A)(\cos A)}=\frac{2+2 \sin A}{(1+\sin A)(\cos A)}$

$=\frac{2(1+\sin A)}{(1+\sin A)(\cos A)}=\frac{2}{\cos A}=2 \sec A$

$=R . H . S .$

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