alleryStart learning →The identity $1 + \tan^2 A$ equals
A$\csc^2 A$
B$\cos^2 A$
C$\sec^2 A$
D$\cot^2 A$
Answer & Solution
Correct answer: C. $\sec^2 A$
1. Dividing $\sin^2 A + \cos^2 A = 1$ by $\cos^2 A$ gives $\tan^2 A + 1 = \sec^2 A$.
2. So $1 + \tan^2 A = \sec^2 A$.
3. (Similarly $1 + \cot^2 A = \csc^2 A$.)
_Source: Karnataka SSLC (KSEEB) Class 10 Mathematics, Ch11 'Introduction to Trigonometry', §11.4_
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