- #1
fireflies
- 210
- 12
I know a tangent drawn on parabola having equation like
y^2=4ax is
y=mx+(a/m)
which provides c=a/m
Then how is it going to turn for equation like x^2=4ay?
From my derivation it will be like -c=am^2
when the equation of tangent is y=mx+c.
The derivation comes from the following:
y=mx+c
or, x=(y/m)-(c/m)
So, comparing with the tangent on
y^2=4ax we get
-(c/m)=a/(1/m)
that is -c= am^2
But the problem arises when in a question saying find the common tangent on y^2=4ax and x^2=4ay, the solution was made taking the tangents for each parabola as
y=mx+a/m and
x= my + a/m respectively.
Shouldn't the later one be x=(y/m)-(c/m)
i.e x=(y/m)-am ?
y^2=4ax is
y=mx+(a/m)
which provides c=a/m
Then how is it going to turn for equation like x^2=4ay?
From my derivation it will be like -c=am^2
when the equation of tangent is y=mx+c.
The derivation comes from the following:
y=mx+c
or, x=(y/m)-(c/m)
So, comparing with the tangent on
y^2=4ax we get
-(c/m)=a/(1/m)
that is -c= am^2
But the problem arises when in a question saying find the common tangent on y^2=4ax and x^2=4ay, the solution was made taking the tangents for each parabola as
y=mx+a/m and
x= my + a/m respectively.
Shouldn't the later one be x=(y/m)-(c/m)
i.e x=(y/m)-am ?