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If cot3θ⋅cot6θ=1cot3\theta \cdot cot6\theta = 1cot3θ⋅cot6θ=1, then the value of tan15θtan15\thetatan15θ will be​
Question

If cot3θcot6θ=1cot3\theta \cdot cot6\theta = 1, then the value of tan15θtan15\theta will be​

A.

3-\sqrt{3}​​

B.

0

C.

13-\frac{1}{\sqrt{3}}​​

D.

333\sqrt{3}​​

Correct option is C

Given:

cot⁡(3θ) cot⁡(6θ) =1

Concept Used:

We know the identity:

For,  A+B=π2A+B= \frac{\pi}{2}  

cotAcotB=1\cot A \cdot \cot B = 1​​

Solution:

3θ + 6θ = π2\frac{\pi}{2} 

9θ = π2\frac{\pi}{2} 

​θ = π18\frac{\pi}{18} 

Then, value of tan⁡ (15θ) 

θ = π18\frac{\pi}{18} = 15​θ = 15 ×π18\times\frac{\pi}{18} = 5π6\frac{5\pi}{6} 

Then, 

tan(5π6)=tan(ππ6)=tan(π6)=13\tan\left(\frac{5\pi}{6}\right) = -\tan\left(\pi - \frac{\pi}{6}\right) = -\tan\left(\frac{\pi}{6}\right) = -\frac{1}{\sqrt{3}} 

​So, the value of tan(15θ)\tan(15\theta)​ is: 13-\frac{1}{\sqrt{3}} 


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