Calculus - Tangent lines and radial lines

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SUMMARY

The discussion focuses on the relationship between tangent lines and radial lines in polar coordinates, specifically for a curve defined by r=f(θ). It establishes that the angle ψ between the tangent line at point P and the radial line OP can be expressed as tan(ψ) = r/(dr/dθ), where dr/dθ is the derivative f'(θ). The equations y = r*sin(θ) and x = r*cos(θ) are also referenced to facilitate the conversion between polar and Cartesian coordinates.

PREREQUISITES
  • Understanding of polar coordinates and curves defined by r=f(θ)
  • Knowledge of derivatives, specifically f'(θ)
  • Familiarity with trigonometric functions and their relationships
  • Basic skills in converting between polar and Cartesian coordinates
NEXT STEPS
  • Study the derivation of polar coordinates and their applications in calculus
  • Learn about the concept of tangent lines in the context of polar curves
  • Explore the implications of the derivative f'(θ) in polar equations
  • Investigate the relationship between angles in polar coordinates and their Cartesian equivalents
USEFUL FOR

Students studying calculus, particularly those focusing on polar coordinates and their applications in geometry and physics.

RentonT
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Homework Statement


Let P be any point (except the origin) on the curve r=f(θ). If ψ is the angle between the tangent line at P and the radial line OP, show that

tan(ψ)= (r/(dr/dθ))​

Hint: Observe that ψ = φ - θ in the figure.

Homework Equations


Very few equations come to mind except y = r*sin(θ) and x = r*cos(θ). Also, dr/dθ is equal to f'(θ).


The Attempt at a Solution


See Relevant Equations.
 
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Note that:
[tex] \tan (\psi )=\frac{dy}{dx}[/tex]
In cartesian co-ordinates.
 

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