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Locus and the parabola question (1 Viewer)

Pinkled

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From maths in focus extension 1 book by margaret grove:
ex 11.7 question 14.

Find the equation of the tangent at (8,4) on the parabola x^2=16y.
This tangent meets the tangent at the vertex of the parabola at point R. Find the coordinates of R.

i got the equation but had no idea how to find the coordinates, any help please?
Thankyou
 

Carrotsticks

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The tangent at the vertex is quite clearly a horizontal line (draw a diagram you will see).

But since the vertex lies on the X axis, the tangent is the X axis itself!

So finding the point of intersection between the two tangents is equivalent to finding the X intercept of the tangent you found.
 

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