Q. 13 A3.9( 12 Votes )

If sin 10θ = cos8θ and 10θ is a positive acute angle, let us find the value of tan 9θ.

Answer :

Given, sin10θ = cos8θ

And 10θ is a positive acute angle

sin10θ = cos8θ

cos(90 - 10θ) = cos8θ

90 - 10θ = 8θ

90 = 18θ

θ = 5

Hence, the value of θ is 5

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