Editing Polar coordinate system (section)

===Line===
''Radial'' lines (those running through the pole) are represented by the equation
<math display="block">\varphi = \gamma,</math>
where <math>\gamma</math> is the angle of elevation of the line; that is, <math>\varphi = \arctan m</math>, where <math>m</math> is the [[slope]] of the line in the Cartesian coordinate system. The non-radial line that crosses the radial line <math>\varphi = \gamma</math> [[perpendicular]]ly at the point <math>(r_0, \gamma)</math> has the equation
<math display="block">r(\varphi) = r_0 \sec(\varphi - \gamma).</math>

Otherwise stated <math>(r_0, \gamma)</math> is the point in which the tangent intersects the imaginary circle of radius <math>r_0</math>