3.Trigonometrical Ratios, Functions and Identities
medium

यदि $\sin A,\cos A$ तथा $\tan A$ गुणोत्तर श्रेणी में हों, तब ${\cos ^3}A + {\cos ^2}A$ का मान है  

A

$1$

B

$2$

C

$4$

D

इनमें से कोई नहीं

Solution

यहाँ $\sin A,\,\cos A$ एवं $\tan A$ गुणोत्तर श्रेणी में हैं

${\cos ^2}A = \sin A\,\tan A = \frac{{{{\sin }^2}A}}{{\cos A}}\,$

$\Rightarrow \,{\cos ^3}A – {\sin ^2}A = 0$

अत: ${\cos ^3}A + {\cos ^2}A = {\sin ^2}A + {\cos ^2}A = 1$

Standard 11
Mathematics

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