How can we derive a polar equation from the Cartesian equation xy = 1?

To find a polar equation corresponding to the Cartesian equation xy = 1, we start by recalling the relationships between Cartesian and polar coordinates. In polar coordinates, x and y can be expressed as:

  • x = r imes ext{cos}( heta)
  • y = r imes ext{sin}( heta)

Here, r is the radial distance from the origin, and θ is the angle measured from the positive x-axis.

Substituting these expressions for x and y into the equation gives:

(r imes ext{cos}( heta))(r imes ext{sin}( heta)) = 1

This simplifies to:

r^2 imes ext{cos}( heta) imes ext{sin}( heta) = 1

Next, we can use the identity 2 imes ext{cos}( heta) imes ext{sin}( heta) = ext{sin}(2 heta) to rewrite the equation:

r^2 imes rac{1}{2} imes ext{sin}(2 heta) = 1

This leads to:

r^2 = rac{2}{ ext{sin}(2 heta)}

To express r in terms of θ, we take the square root:

r = rac{ ext{sqrt}(2)}{ ext{sqrt}( ext{sin}(2 heta))}

Thus, the polar equation corresponding to the Cartesian equation xy = 1 is:

r = rac{ ext{sqrt}(2)}{ ext{sqrt}( ext{sin}(2 heta))}

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