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Question

Mathematics Question on Trigonometric Functions

The value of tan10tan20tan30tan40tan50tan60tan70tan80=\tan 10^{\circ}\, \tan 20^{\circ} \, \tan 30^{\circ} \, \tan 40^{\circ} \, \tan 50^{\circ}\, \tan 60^{\circ} \tan 70^{\circ} \, \tan 80^{\circ} =

A

0

B

-1

C

13 \frac{1}{\sqrt{3}}

D

1

Answer

1

Explanation

Solution

tan10tan20tan30tan40tan50tan60tan70tan80\tan 10^{\circ}\, \tan 20^{\circ} \, \tan 30^{\circ} \, \tan 40^{\circ} \, \tan 50^{\circ}\, \tan 60^{\circ} \tan 70^{\circ} \, \tan 80^{\circ}
=tan(9080)tan(9070)tan(9060)tan(9050)tan50tan60tan70tan80= \tan (90 - 80)^{\circ} \tan (90 - 70)^{\circ} \tan (90 - 60)^{\circ} \tan (90 - 50)^{\circ} \tan 50^{\circ} \tan 60^{\circ} \tan 70^{\circ} \tan 80^{\circ}
=tan80×cot80×tan70×cot70×tan60×cot60×tan50×cot50=1= \tan 80^{\circ} \times \cot 80^{\circ} \times \tan 70^{\circ} \times \cot 70^{\circ} \times \tan 60^{\circ} \times \cot 60^{\circ} \times \tan 50^{\circ} \times \cot 50^{\circ} = 1