If sin 10θ = cos8θ and 10θ is a positive acute angle, then find the value of tan9θ. Solution : sin 10θ = cos8θ [ ∵ sin ( 90 – θ ) = cos = θ ] ⇒ sin 10θ = sin ( 90 – 8θ ) ⇒ 10θ = 90- 8θ ⇒ 10Θθ + 8θ = 90 ⇒ 18θ = 90 ⇒ θ = 90 / 18 ⇒ θ = 5 Now, tan 9θ = tan ( 9 × 5) = tan 45° = 1 Categories: Class 10 Maths TutorialsMathematics Tutorials 0 Comments Leave a Reply Cancel replyYou must be logged in to post a comment.

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