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# c4 - dx/dy - finding equation of normal watch

1. I am doing c4 parametric equations.

dx/dy has come out as -3sint. When I replace t with the value given, I get -3/2. The reciprical obviously gives 2/3

Can I then just manipulate the equation of a straight line?

Instead of using y-y1= x (x-x1) can I just use x-x1 = y (y-y1) ?

Or is that not how it works?

I have tried reversing -3sint in order to get dy/dx but it doesn't give me the right answer.
2. isnt dx/dy simply 1/(dy/dx)? for example say you had gradient :-2 for the tangent, so for the normal it becomes 1/2, so dx/dy = 1/(1/2) which is 2.
3. (Original post by RedGold)
dx/dy has come out as -3sint
do you mean dx/dt?

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