Choose the correct value of $\dfrac{1+\tan^2 A}{1+\cot^2 A}$.
A$\sec^2 A$
B$-1$
C$\cot^2 A$
D$\tan^2 A$
Answer & Solution
Correct answer: D. $\tan^2 A$
Using identities, $1+\tan^2 A=\sec^2 A$ and $1+\cot^2 A=\cosec^2 A$. So
$$\frac{1+\tan^2 A}{1+\cot^2 A}=\frac{\sec^2 A}{\cosec^2 A}=\frac{1/\cos^2 A}{1/\sin^2 A}=\frac{\sin^2 A}{\cos^2 A}=\tan^2 A.$$
Thus option D is correct.
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