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Locus: Help please (1 Viewer)

Jkitty

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3. Find the point of intersection between the
i. tangent
Ii. Normal to the curve
A. x^2=4y at the points (2p,p^2) and 2q,q^2)


Thank you :)
 

braintic

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That is just bookwork. It should be in your notes. Or look in the textbook.
 

Jaguar33

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i found out how to do it! Right, so first for i) tangent,

1. You differentiate x^2=4y, which will give you a gradient of p.
2. Use the equation formula (y-y1)=m(x-x1)
and place the first points in (2p, p^2)
this will give you an equation of y=px - p^2

Then do this step again, except with the other points (2q,q^2)
and you will get y=qx-q^2

Make the two equations you have found, and make them equal each other. Then proceed, to put any terms with x on the left side, and the other on p side,
Then factorise
So it will look like this by now
x(p-q) = p(p-q)(p+q)
cross out, then you have the first point of intersection for x= p +q. Then sub this back in to get why

and i havent done the 2nd part, but im guessing u do the same for the normal :)
 

Jkitty

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i found out how to do it! Right, so first for i) tangent,

1. You differentiate x^2=4y, which will give you a gradient of p.
2. Use the equation formula (y-y1)=m(x-x1)
and place the first points in (2p, p^2)
this will give you an equation of y=px - p^2

Then do this step again, except with the other points (2q,q^2)
and you will get y=qx-q^2

Make the two equations you have found, and make them equal each other. Then proceed, to put any terms with x on the left side, and the other on p side,
Then factorise
So it will look like this by now
x(p-q) = p(p-q)(p+q)
cross out, then you have the first point of intersection for x= p +q. Then sub this back in to get why

and i havent done the 2nd part, but im guessing u do the same for the normal :)
Thank you so much :)
 

braintic

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You should be asking your teacher why they haven't given you an example of this in class.
 

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