Q. 9 A55.0( 4 Votes )

# If 2 cos 3 θ = 1, then the value of θ is

A. 10^{o}

B. 15^{o}

C. 20^{o}

D. 30^{o}

Answer :

Given,

⇒ we know

∴ θ = 20

⇒ cos3(20) = cos60

⇒ Option A is incorrect as it does not satisfy the value

⇒ Option B is incorrect as it does not satisfy the value

⇒ Option D is incorrect as it does not satisfy the value

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Let us eliminate ‘θ’ from the relations :

5x = 3 sec θ, y = 3 tan θ

West Bengal Board - MathematicsLet us fill in the blanks :

i. The value of is ________.

ii. If then the value of cos θ is __________

iii. If then the value of cos^{4}θ – sin^{4}θ is __________

If and then let us determine the values of both r and θ.

West Bengal Board - MathematicsIf sin θ + sin^{2} θ = 1, then let us prove that, cos^{2} θ + cos^{4} θ = 1.

If 2x = sec A and then the value of is

West Bengal Board - MathematicsIf 2 cos 3 θ = 1, then the value of θ is

West Bengal Board - MathematicsIf then let us show that,

West Bengal Board - MathematicsIf and sec θ + cosec θ + x, then the value of x is

West Bengal Board - Mathematics