Can you prove \tan 20^{\circ}+4 \sin 20^{\circ}=\sqrt{3}?

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Discussion Overview

The discussion revolves around the proof of the equation $$\tan 20^{\circ}+4 \sin 20^{\circ}=\sqrt{3}$$. It includes mathematical reasoning and attempts to derive the relationship using trigonometric identities.

Discussion Character

  • Mathematical reasoning

Main Points Raised

  • One participant presents a series of trigonometric identities and transformations to show that $$\tan 20^{\circ}+4 \sin 20^{\circ}$$ simplifies to $$\sqrt{3}$$ by relating it to $$\tan 60^{\circ}$$.
  • Another participant reiterates the same mathematical steps, confirming the approach and expressing appreciation for the method used.

Areas of Agreement / Disagreement

There appears to be agreement on the method used to derive the proof, but the discussion does not clarify whether all participants accept the conclusion as established fact.

Contextual Notes

The discussion relies on specific trigonometric identities and transformations, and the validity of the proof may depend on the assumptions made regarding the angles involved.

anemone
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Prove that $$\tan 20^{\circ}+4 \sin 20^{\circ}=\sqrt{3}$$.
 
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anemone said:
Prove that $$\tan 20^{\circ}+4 \sin 20^{\circ}=\sqrt{3}$$.

we have tan 60 - tan 20
=sin 60/cos 60 - sin 20/cos 20
= (sin 60 cos 20 - cos 60 sin 20)/ ( cos 60 cos 20)
= sin (60-20)/ (cos 60 cos 20)
= sin 40/ ( cos 60 cos 20)
= (2 sin 20 cos 20)/( cos 60 cos 20)
= 2 sin 20 / cos 60
= 2 sin 20/ (1/2) = 4 sin 20

hence 4 sin 20 + tan 20 = tan 60 = 3^(1/2)
 
kaliprasad said:
we have tan 60 - tan 20
=sin 60/cos 60 - sin 20/cos 20
= (sin 60 cos 20 - cos 60 sin 20)/ ( cos 60 cos 20)
= sin (60-20)/ (cos 60 cos 20)
= sin 40/ ( cos 60 cos 20)
= (2 sin 20 cos 20)/( cos 60 cos 20)
= 2 sin 20 / cos 60
= 2 sin 20/ (1/2) = 4 sin 20

hence 4 sin 20 + tan 20 = tan 60 = 3^(1/2)

Thanks for participating, kaliprasad and I like your method in cracking this problem so much!
 
anemone said:
Thanks for participating, kaliprasad and I like your method in cracking this problem so much!

Thanks anemone. As long as you ask questions whether I answer or not I shall not get Alzheimer's disease.
 

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