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3.Trigonometrical Ratios, Functions and Identities
easy
यदि $\cos 3\theta = \alpha \cos \theta + \beta {\cos ^3}\theta ,$ तो $(\alpha ,\beta ) = $
A
$(3,\,4)$
B
$(4,\,3)$
C
$( - 3,\,4)$
D
$(3,\, - 4)$
Solution
(c) दिया है $\cos 3\theta $
$= \alpha \cos \theta + \beta {\cos ^3}\theta $
लेकिन $\cos 3\theta = 4{\cos ^3}\theta – 3\cos \theta $
==> $(\alpha ,\beta ) = ( – 3,\,4)$.
Standard 11
Mathematics