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Find the value of tan⁡15o+cot⁡15o\tan{15^o} + \cot{15^o}tan15o+cot15o​​
Question

Find the value of tan15o+cot15o\tan{15^o} + \cot{15^o}​​

A.

4

B.

6

C.

8

D.

2

Correct option is A

To find: 

​cot15° + tan15°

Formula used:

Sin2θ+Cos2θ=1tanθ=sinθcosθ,Cotθ=cosθsinθSin2θ=2sinθcosθSin^2\theta + Cos^2\theta = 1\\[5pt]tan\theta= \frac{sin\theta}{cos\theta},\\[5pt] Cot\theta= \frac{cos\theta}{sin\theta}\\[5pt]Sin2\theta = 2 sin\theta cos\theta ​​

Solution:

cot15° + tan15°

=> (cos15°/sin15°) + (sin15°/cos15°)

=> (cos215°+sin215°)(sin15°cos15°)\frac{(cos^215° + sin^2 15°)}{(sin15° cos 15°)}​   (Sin2θ + cos2θ = 1)

=> 1(sin15°cos15°)\frac{1}{(sin15° cos15°)}​​

Multiply and divide equation by 2

=> 2(2sin15°cos15°)\frac{2}{(2 sin15° cos15°)}​    (2 sinθ cosθ = sin2θ)

=> 2sin30°\frac{2}{sin30°} ​     (sin30° = 1/2)

=> (2/1/2) = 2 × 2

=> 4

Hence, option (a) is the correct answer.

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