SATHEE: Trigonometric Identities Question 54

Trigonometric Identities Question 54

Question: $ \cos 20{}^\circ \cos 40{}^\circ \cos 80{}^\circ = $

[MP PET 1989]

Options:

A) 1/2

B) 1/4

C) 1/6

D) 1/8

Show Answer

Answer:

Correct Answer: D

Solution:

$ \cos 20^{o}\cos 40^{o}\cos 80^{o}=\frac{\sin 2^{3}20^{o}}{2^{3}\sin 20^{o}} $ $ =\frac{\sin 160^{o}}{8\sin 20^{o}}=\frac{1}{8} $ .

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Trigonometric Identities Question 54

Question: $ \cos 20{}^\circ \cos 40{}^\circ \cos 80{}^\circ = $

Options:

Answer:

Solution:

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