Sin {163^o}cos {347^o} + sin {73^o}sin {167^o} =

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3.Trigonometrical Ratios, Functions and Identities

easy

$\sin {163^o}\cos {347^o} + \sin {73^o}\sin {167^o} = $

A

$0$

B

$1/2$

C

$1$

D

None of these

Solution

(b) $\sin {163^o}\cos {347^o} + \sin {73^o}\sin {167^o}$

$ = \sin ({180^o} – {17^o})\cos ({360^o} – {13^o}) + \cos ({90^o} – {17^o}) \sin ({180^o} – {13^o})$

$ = \sin {17^o}\cos {13^o} + \cos {17^o}\sin {13^o}$

$ =\sin {30^o} = 1/2$.

Standard 11

Mathematics

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