Equally inclined tangents of an ellipse

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SUMMARY

The discussion focuses on finding the equations of the tangents to the ellipse defined by the equation 4x² + 9y² = 36, which are equally inclined to the x and y axes. The solution involves substituting y = mx + c into the ellipse equation and analyzing the quadratic discriminant, leading to the conclusion that c² = 9m² + 4. It is established that "equally inclined" implies the slopes of the tangent lines must be ±1, confirming the need for calculus methods in the solution.

PREREQUISITES
  • Understanding of ellipse equations, specifically 4x² + 9y² = 36
  • Knowledge of quadratic discriminants in algebra
  • Familiarity with the concept of slopes and tangent lines
  • Basic calculus concepts related to derivatives and tangent calculations
NEXT STEPS
  • Study the properties of ellipses and their tangent lines
  • Learn about quadratic discriminants and their applications in conic sections
  • Explore calculus techniques for finding tangents to curves
  • Investigate the geometric interpretation of slopes in relation to axes
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Students studying conic sections, particularly those tackling calculus problems involving ellipses and tangent lines, as well as educators looking for examples of applying quadratic discriminants in geometry.

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Homework Statement


Find the equation of the tangents to the ellipse 4x^2+9y^2 = 36 which are equally inclined to the x and y-axis.

Homework Equations


Quadratic discriminant

The Attempt at a Solution


First I substituted y=mx+c into the ellipse, and determined its discriminant, and got c^2 = 9m^2 + 4
 
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sooyong94 said:

Homework Statement


Find the equation of the tangents to the ellipse 4x^2+9y^2 = 36 which are equally inclined to the x and y-axis.

Homework Equations


Quadratic discriminant

The Attempt at a Solution


First I substituted y=mx+c into the ellipse, and determined its discriminant, and got c^2 = 9m^2 + 4
Doesn't "equally inclined" to the x and y axes mean that the slopes of the tangent lines have to be 1 or -1?

Also, I'm reasonably sure that this is a calculus problem, so it should not be posted in the Precalc section. I'm moving it to the Calc & Beyond section.
 

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