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3.Trigonometrical Ratios, Functions and Identities
easy
If $\sin x + {\rm{cosec}}\,x = 2,$ then $sin^n x + cosec^n x$ is equal to
A
$2$
B
${2^n}$
C
${2^{n - 1}}$
D
${2^{n - 2}}$
Solution
(a) $\sin x + \cos {\rm{ec}}x = 2$
$\Rightarrow {(\sin x – 1)^2} = 0 \Rightarrow \sin x = 1$
$\therefore {\sin ^n}x + {\rm{cose}}{{\rm{c}}^n}x = 1 + 1 = 2$ .
Standard 11
Mathematics