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Conics Hyperbola Question (1 Viewer)

Vizsla

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2015
Here is the question.

P is a variable point on the standard hyperbola with focus S. PT is tangent at P and ST is perpendicular to PT.

Show that T lies on the circle x^2 + y^2 = a^2.

any help is appreciated
 

dan964

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I'll give you steps instead...
1. Let P represent (a sec theta, b tan theta)
2. Find dy/dx, and sub P into to find gradient of PT. Find equation of PT
3. Find equation of PS, using S as the point, and -1/m as the gradient, where m is the gradient of PT.
4. Solve equations from (2) and (3) simulateneously to find co-ordinates of T.
5. Eliminate the parameter (theta) by substitution into given result or otherwise.
 

Vizsla

Member
Joined
Dec 18, 2014
Messages
45
Location
Sydney
Gender
Male
HSC
2015
I'll give you steps instead...
1. Let P represent (a sec theta, b tan theta)
2. Find dy/dx, and sub P into to find gradient of PT. Find equation of PT
3. Find equation of PS, using S as the point, and -1/m as the gradient, where m is the gradient of PT.
4. Solve equations from (2) and (3) simulateneously to find co-ordinates of T.
5. Eliminate the parameter (theta) by substitution into given result or otherwise.
Did you go to sydney tech?
 

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