Simplify Trig Equation by Hand: (Cos[x]^2) (Tan[x] + Cot[x]) = Sin[x]*Cos^3[x]

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SUMMARY

The forum discussion centers on simplifying the trigonometric equation (Cos[x]^2)(Tan[x] + Cot[x]) to Sin[x]*Cos^3[x]. The correct simplification process involves recognizing that (Cos[x]^2)(Sin[x]/Cos[x] + Cos[x]/Sin[x]) leads to Sin[x]*Cos^3[x] after appropriate algebraic manipulation. Participants confirm that the final result is indeed cot(x), and graphing tools validate the equivalence of the expressions. The discussion highlights common pitfalls in simplification, particularly the importance of careful division.

PREREQUISITES
  • Understanding of trigonometric identities, specifically Tan[x] and Cot[x]
  • Familiarity with algebraic manipulation of trigonometric functions
  • Knowledge of the Pythagorean identity Sin^2[x] + Cos^2[x] = 1
  • Experience with graphing functions to verify equivalence
NEXT STEPS
  • Study the derivation of trigonometric identities and their applications
  • Practice simplifying complex trigonometric expressions using algebraic techniques
  • Explore graphing calculators or software to visualize trigonometric functions
  • Learn about common mistakes in trigonometric simplification and how to avoid them
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Students studying trigonometry, educators teaching trigonometric identities, and anyone looking to improve their algebraic manipulation skills in trigonometric contexts.

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Homework Statement



(Cos[x]^2) (Tan[x] + Cot[x]) Simplify the equation by hand!

Homework Equations


The Attempt at a Solution



cos^2 / (tan + cot)
cos^2 / (sin/cos + cos/sin) * sin*cos/(sin*cos)
sin*cos^3 / (sin^2 + cos^2)
sin*cos^3 / 1
sin(x) * cos^3(x)

this is wrong b/c i divided it...

NVM found the answer:

(cos^2(x))(sin(x)/cos(x) + cos(x)/sin(x))
cos(x)sin(x) + cos^3(x)/sin(x)
cos(x)sin(x) + cos^2(x)cos(x)/sin(x)
cos(x)sin(x) + (1 - sin^2(x))cos(x)/sin(x)
cos(x)sin(x) + (cos(x) - sin^2(x)cos(x))/sin(x)
cos(x)sin(x) + cot(x) - sin(x)cos(x)
cot(x)
 
Last edited:
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Sorry, it's wrong because you divided what?

\frac{cos^2x}{tanx+cotx}\equiv sinx. cos^3x

The question says simplify cos^2x(tanx+cotx). Was this a typo?
 
It's hard to read what you've done... And I can tell you now that it's not equivalent to cot(x).
 
I get cot(x) as well, though you can skip quite a few steps in the simplification.
Graphing confirms these are equivalent.
 

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