Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Two Parabola Problems

  1. May 14, 2014 #1
    I am not able to solve the following problem

    #1) Prove that the normal to parabola y2=4ax at (am2,-2am) intersects the parabola again at an angle tan-1(m/2)

    What I am thinking is to solve the equation of parabola and equation of normal y=mx-am-3-2am simultaneously and at that point I will find the slope of tangent and will get the angle between tangent and normal. The problem is that answer is not coming.

    #2) For what values of a will the tangents drawn to parabola y2=4ax from a point , not on the y-axis, will be normals to the parabola x2=4y?

    I have no idea on how to solve this question
    Thanks in Advance
  2. jcsd
  3. May 14, 2014 #2

    Simon Bridge

    User Avatar
    Science Advisor
    Homework Helper

    Start with the first one to begin with.

    Please show your working?
    Show each step with your reasoning.
    It can hep to reverse the roles of the x and y axes.

    The key to the second one is to rewrite the problem statement in maths.
    i.e. a point not on the y axis is point ##p=(p_x,p_y): p_x\neq 0##
  4. May 14, 2014 #3
    I got the #1 problem, I was making it more lengthy.
  5. May 14, 2014 #4

    Simon Bridge

    User Avatar
    Science Advisor
    Homework Helper

    OK - so what about #2?
    Same suggestions.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Similar Threads for Parabola Problems
I Problems in Differential geometry