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3.Trigonometrical Ratios, Functions and Identities
easy
જો $\sin {\theta _1} + \sin {\theta _2} + \sin {\theta _3} = 3,$ તો $\cos {\theta _1} + \cos {\theta _2} + \cos {\theta _3} = $
A
$3$
B
$2$
C
$1$
D
$0$
Solution
(d) $\sin {\theta _1} + \sin {\theta _2} + \sin {\theta _3} = 3$
$ \Rightarrow \sin {\theta _1} = \sin {\theta _2} = \sin {\theta _3} = 1$, $( \because – 1 \le \sin x \le 1)$
$ \Rightarrow {\theta _1} = {\theta _2} = {\theta _3} = \frac{\pi }{2} $
$\Rightarrow \cos {\theta _1} + \cos {\theta _2} + \cos {\theta _3} = 0$.
Standard 11
Mathematics
