Questions asked by venkata k.

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• Why parametric equations of the parabola #y^2 = 4ax# is #y =2at# and #x = at^2# . why can't #y =4at# and #x = 4at^2#. Because #y = 4at# and #x = 4at^2# also satisfies the equation #y^2 = 4ax# right ?
  
• Why square root functions are taken as positive, why can't negative ? eg #f(x) = (25 - x^2)^(1/2)#
  
• Why directrix is taken on the major axis of ellipse. Why can't we take directrix on minor axis of ellipse ?