Simplifying trig expression

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SUMMARY

The discussion focuses on simplifying the trigonometric expression \(\cot(\frac{2\pi}{3} - x)\) using the tangent subtraction identity. The identity \(\tan(A - B) = \frac{\tan A - \tan B}{1 + \tan A \tan B}\) is applied to derive the expression. The final simplified form is \(\frac{\sqrt{3}\tan x - 1}{\tan x + \sqrt{3}}\), demonstrating a clear transformation from the original expression to a more manageable format.

PREREQUISITES
  • Understanding of trigonometric identities, specifically the tangent subtraction identity.
  • Familiarity with cotangent and tangent functions.
  • Knowledge of reference angles in trigonometry.
  • Basic algebraic manipulation skills.
NEXT STEPS
  • Study the derivation of the tangent subtraction identity in detail.
  • Practice simplifying various trigonometric expressions using identities.
  • Explore the relationship between cotangent and tangent functions.
  • Learn about reference angles and their applications in trigonometry.
USEFUL FOR

Students and educators in mathematics, particularly those focusing on trigonometry, as well as anyone looking to enhance their skills in simplifying trigonometric expressions.

hatelove
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I have to simplify (or get it in terms of tan I guess?) \cot (\frac{2\pi }{3} - x)

R08ta.png


I'm not sure how to get the reference angle and subtract the angle 'x' from it to get an expressional value...how would I do this?
 
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Hello, daigo!

\text{Simplify: }\:\cot(\tfrac{2\pi}{3} - x)
\text{Identity: }\:\tan(A - B) \;=\;\frac{\tan A - \tan B}{1 + \tan A\tan B}

\cot(\tfrac{2\pi}{3} - x) \;=\;\frac{1}{\tan(\frac{2\pi}{3} - x)} \;=\;\frac{1 + \tan\frac{2\pi}{3}\tan x}{\tan\frac{2\pi}{3} - \tan x}

. . . . . . . . .=\; \frac{1 + (\text{-}\sqrt{3})\tan x}{(\text{-}\sqrt{3}) - \tan x} \;=\; \frac{1 - \sqrt{3}\tan x}{\text{-}\sqrt{3} - \tan x}

. . . . . . . . .=\; \frac{\sqrt{3}\tan x - 1}{\tan x + \sqrt{3}}
 

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