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# rectangular hyperbola watch

1. also last minute i cant figure out what to do
ok for part a) they said to prove that the tangent to the rectangular hyperbola with equation xy=c^2 (c>0) at the point (ct, c/t)
is this : t^2(y) + x = 2ct

i done that part
b)then the y say tangents are drawn from the point (-3,3) to the rectangular hyperbola with equation xy=16.
find the coordinates of the points of contact of these tangents with the hyperbola.

any help with b? please exam in an hr and a half!
2. (Original post by kriztinae)
also last minute i cant figure out what to do
ok for part a) they said to prove that the tangent to the rectangular hyperbola with equation xy=c^2 (c>0) at the point (ct, c/t)
is this : t^2(y) + x = 2ct

i done that part
b)then the y say tangents are drawn from the point (-3,3) to the rectangular hyperbola with equation xy=16.
find the coordinates of the points of contact of these tangents with the hyperbola.

any help with b? please exam in an hr and a half!
xy = 16
c = ±4

substitute into t^2(y) + x = 2ct

t²y + x = ±8t

the point (-3,3) satisfies this eqn - so substitute x=-3, y=3 and solve for t.
Hence the tangent pts (ct, c/t)
3. (Original post by Fermat)
xy = 16
c = ±4

substitute into t^2(y) + x = 2ct

t²y + x = ±8t

the point (-3,3) satisfies this eqn - so substitute x=-3, y=3 and solve for t.
Hence the tangent pts (ct, c/t)
thanx but i just did my exam and it didnt come up thankfull! no more p5! forever!!!!!

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