## Re: Conics

Expand Messages
• yeah ^_^||| coz i havta prep for public exam, argh... anyway, glad that u remember me and is still around w/ slim. btw, i havta wear mask during all my
Message 1 of 7 , Apr 30, 2003
yeah ^_^||| coz i havta prep for public exam, argh...

anyway, glad that u remember me and is still around w/ slim.

btw, i havta wear mask during all my examinations! becoz of the
atypical pneumonia! well, i live in Hong Kong, and that's quite self-
explanatory... >_< im always trapped at home!

--- In mathforfun@yahoogroups.com, clooneman <no_reply@y...> wrote:
> You've not been around for ages, have you?
>
> --- In mathforfun@yahoogroups.com, cs_smile <no_reply@y...> wrote:
> > can anybody help me out? i am desperate, coz im gonna have my
open
> > exam next week. I would be grateful if anyone can help!
> > Thx!
> >
> > --- In mathforfun@yahoogroups.com, cs_smile <no_reply@y...> wrote:
> > > pls help!
> > >
> > > here's the problem:
> > >
> > > note: pls refer to the photos>problems> conics1 and conics 2
pics
> > > for the diagrams.
> > >
> > > (a) Figure 6(a) shows three straight lines L1:y=k, L2 which has
a
> > > slpe m and L, all of them pass through the point (h,k) and L2
is
> > the
> > > angle bisector of L and L1.
> > >
> > > (1) Let @ and (@2) be the inclinations of L and L2
> > > respectively. Show that @=2(@2)-180.
> > > (2) Hence, or otherwise, find the equation of L, in
terms of
> > > h, k and m.
> > >
> > > (b) (1) Figure 6(b) shows part of a circle C: x^2+y^2=r^2,
where
> r
> > > is a positive constant. P(r cos @, r sin @) is a point on C. L3
> > and
> > > L4 are straight lines passing through P with L3 parallel to the
x-
> > > axis.
> > > (i) Find the slope, in terms of @, of the normal to C
at P.
> > > (ii) Using (a), or otherwise, find the equation of L4 in
terms
> > > of @.
> > >
> > > (2) Figure 6(c) shows a parabola S: y^2=4ax, where a is
a
> > > positive constant. Q(at^2, 2at) is a point on S. L5 and L6 are
> > > straight lines passing through Q with L5 parallel to the x-axis.
> > > (i) Find the slope, in terms of @, of the normal to S
at Q.
> > > (ii) Find the equation of L6 in terms of t.
> > >
> > > (c) A student wants to use a curve mirror to focus a parallel
> > light
> > > beam to a fixed point. Explain whether he should use a circular
> > > mirror or a parabolic mirror.
> > >
> > >
> > > thx!
• Is it true that people there can t handle the claustrophobia of confinement and have tried to jump out windows? ... self- ... has ... L3 ... the ... in ... is
Message 2 of 7 , May 1, 2003
Is it true that people there can't handle the claustrophobia of
confinement and have tried to jump out windows?

--- In mathforfun@yahoogroups.com, cs_smile <no_reply@y...> wrote:
> yeah ^_^||| coz i havta prep for public exam, argh...
>
> anyway, glad that u remember me and is still around w/ slim.
>
> btw, i havta wear mask during all my examinations! becoz of the
> atypical pneumonia! well, i live in Hong Kong, and that's quite
self-
> explanatory... >_< im always trapped at home!
>
> --- In mathforfun@yahoogroups.com, clooneman <no_reply@y...> wrote:
> > You've not been around for ages, have you?
> >
> > --- In mathforfun@yahoogroups.com, cs_smile <no_reply@y...> wrote:
> > > can anybody help me out? i am desperate, coz im gonna have my
> open
> > > exam next week. I would be grateful if anyone can help!
> > > Thx!
> > >
> > > --- In mathforfun@yahoogroups.com, cs_smile <no_reply@y...>
wrote:
> > > > pls help!
> > > >
> > > > here's the problem:
> > > >
> > > > note: pls refer to the photos>problems> conics1 and conics 2
> pics
> > > > for the diagrams.
> > > >
> > > > (a) Figure 6(a) shows three straight lines L1:y=k, L2 which
has
> a
> > > > slpe m and L, all of them pass through the point (h,k) and L2
> is
> > > the
> > > > angle bisector of L and L1.
> > > >
> > > > (1) Let @ and (@2) be the inclinations of L and L2
> > > > respectively. Show that @=2(@2)-180.
> > > > (2) Hence, or otherwise, find the equation of L, in
> terms of
> > > > h, k and m.
> > > >
> > > > (b) (1) Figure 6(b) shows part of a circle C: x^2+y^2=r^2,
> where
> > r
> > > > is a positive constant. P(r cos @, r sin @) is a point on C.
L3
> > > and
> > > > L4 are straight lines passing through P with L3 parallel to
the
> x-
> > > > axis.
> > > > (i) Find the slope, in terms of @, of the normal to C
> at P.
> > > > (ii) Using (a), or otherwise, find the equation of L4
in
> terms
> > > > of @.
> > > >
> > > > (2) Figure 6(c) shows a parabola S: y^2=4ax, where a
is
> a
> > > > positive constant. Q(at^2, 2at) is a point on S. L5 and L6
are
> > > > straight lines passing through Q with L5 parallel to the x-
axis.
> > > > (i) Find the slope, in terms of @, of the normal to S
> at Q.
> > > > (ii) Find the equation of L6 in terms of t.
> > > >
> > > > (c) A student wants to use a curve mirror to focus a parallel
> > > light
> > > > beam to a fixed point. Explain whether he should use a
circular
> > > > mirror or a parabolic mirror.
> > > >
> > > >
> > > > thx!
• Nope, that is Taiwan. HK medical stuff is more responsible and will never jump out juz to escape. they stay and help the patients to fight the disease... and
Message 3 of 7 , May 2, 2003
Nope, that is Taiwan. HK medical stuff is more responsible and will
never jump out juz to escape. they stay and help the patients to
fight the disease... and risking their lifes...

anyway, do u mind helping me out with this conics problem? im stuck
at finding the equations of the lines after find their slopes. i
cant apply the result in part (a).

--- In mathforfun@yahoogroups.com, clooneman <no_reply@y...> wrote:
> Is it true that people there can't handle the claustrophobia of
> confinement and have tried to jump out windows?
>
> --- In mathforfun@yahoogroups.com, cs_smile <no_reply@y...> wrote:
> > yeah ^_^||| coz i havta prep for public exam, argh...
> >
> > anyway, glad that u remember me and is still around w/ slim.
> >
> > btw, i havta wear mask during all my examinations! becoz of the
> > atypical pneumonia! well, i live in Hong Kong, and that's quite
> self-
> > explanatory... >_< im always trapped at home!
> >
> > --- In mathforfun@yahoogroups.com, clooneman <no_reply@y...>
wrote:
> > > You've not been around for ages, have you?
> > >
> > > --- In mathforfun@yahoogroups.com, cs_smile <no_reply@y...>
wrote:
> > > > can anybody help me out? i am desperate, coz im gonna have
my
> > open
> > > > exam next week. I would be grateful if anyone can help!
> > > > Thx!
> > > >
> > > > --- In mathforfun@yahoogroups.com, cs_smile <no_reply@y...>
> wrote:
> > > > > pls help!
> > > > >
> > > > > here's the problem:
> > > > >
> > > > > note: pls refer to the photos>problems> conics1 and conics
2
> > pics
> > > > > for the diagrams.
> > > > >
> > > > > (a) Figure 6(a) shows three straight lines L1:y=k, L2
which
> has
> > a
> > > > > slpe m and L, all of them pass through the point (h,k) and
L2
> > is
> > > > the
> > > > > angle bisector of L and L1.
> > > > >
> > > > > (1) Let @ and (@2) be the inclinations of L and L2
> > > > > respectively. Show that @=2(@2)-180.
> > > > > (2) Hence, or otherwise, find the equation of L, in
> > terms of
> > > > > h, k and m.
> > > > >
> > > > > (b) (1) Figure 6(b) shows part of a circle C: x^2+y^2=r^2,
> > where
> > > r
> > > > > is a positive constant. P(r cos @, r sin @) is a point on
C.
> L3
> > > > and
> > > > > L4 are straight lines passing through P with L3 parallel
to
> the
> > x-
> > > > > axis.
> > > > > (i) Find the slope, in terms of @, of the normal to C
> > at P.
> > > > > (ii) Using (a), or otherwise, find the equation of L4
> in
> > terms
> > > > > of @.
> > > > >
> > > > > (2) Figure 6(c) shows a parabola S: y^2=4ax, where a
> is
> > a
> > > > > positive constant. Q(at^2, 2at) is a point on S. L5 and L6
> are
> > > > > straight lines passing through Q with L5 parallel to the x-
> axis.
> > > > > (i) Find the slope, in terms of @, of the normal to S
> > at Q.
> > > > > (ii) Find the equation of L6 in terms of t.
> > > > >
> > > > > (c) A student wants to use a curve mirror to focus a
parallel
> > > > light
> > > > > beam to a fixed point. Explain whether he should use a
> circular
> > > > > mirror or a parabolic mirror.
> > > > >
> > > > >
> > > > > thx!
• Nope, that is Taiwan. HK medical stuff is more responsible and will never jump out juz to escape. they stay and help the patients to fight the disease... and
Message 4 of 7 , May 2, 2003
Nope, that is Taiwan. HK medical stuff is more responsible and will
never jump out juz to escape. they stay and help the patients to
fight the disease... and risking their lifes...

anyway, do u mind helping me out with this conics problem? im stuck
at finding the equations of the lines after find their slopes. i
cant apply the result in part (a).

--- In mathforfun@yahoogroups.com, clooneman <no_reply@y...> wrote:
> Is it true that people there can't handle the claustrophobia of
> confinement and have tried to jump out windows?
>
> --- In mathforfun@yahoogroups.com, cs_smile <no_reply@y...> wrote:
> > yeah ^_^||| coz i havta prep for public exam, argh...
> >
> > anyway, glad that u remember me and is still around w/ slim.
> >
> > btw, i havta wear mask during all my examinations! becoz of the
> > atypical pneumonia! well, i live in Hong Kong, and that's quite
> self-
> > explanatory... >_< im always trapped at home!
> >
> > --- In mathforfun@yahoogroups.com, clooneman <no_reply@y...>
wrote:
> > > You've not been around for ages, have you?
> > >
> > > --- In mathforfun@yahoogroups.com, cs_smile <no_reply@y...>
wrote:
> > > > can anybody help me out? i am desperate, coz im gonna have
my
> > open
> > > > exam next week. I would be grateful if anyone can help!
> > > > Thx!
> > > >
> > > > --- In mathforfun@yahoogroups.com, cs_smile <no_reply@y...>
> wrote:
> > > > > pls help!
> > > > >
> > > > > here's the problem:
> > > > >
> > > > > note: pls refer to the photos>problems> conics1 and conics
2
> > pics
> > > > > for the diagrams.
> > > > >
> > > > > (a) Figure 6(a) shows three straight lines L1:y=k, L2
which
> has
> > a
> > > > > slpe m and L, all of them pass through the point (h,k) and
L2
> > is
> > > > the
> > > > > angle bisector of L and L1.
> > > > >
> > > > > (1) Let @ and (@2) be the inclinations of L and L2
> > > > > respectively. Show that @=2(@2)-180.
> > > > > (2) Hence, or otherwise, find the equation of L, in
> > terms of
> > > > > h, k and m.
> > > > >
> > > > > (b) (1) Figure 6(b) shows part of a circle C: x^2+y^2=r^2,
> > where
> > > r
> > > > > is a positive constant. P(r cos @, r sin @) is a point on
C.
> L3
> > > > and
> > > > > L4 are straight lines passing through P with L3 parallel
to
> the
> > x-
> > > > > axis.
> > > > > (i) Find the slope, in terms of @, of the normal to C
> > at P.
> > > > > (ii) Using (a), or otherwise, find the equation of L4
> in
> > terms
> > > > > of @.
> > > > >
> > > > > (2) Figure 6(c) shows a parabola S: y^2=4ax, where a
> is
> > a
> > > > > positive constant. Q(at^2, 2at) is a point on S. L5 and L6
> are
> > > > > straight lines passing through Q with L5 parallel to the x-
> axis.
> > > > > (i) Find the slope, in terms of @, of the normal to S
> > at Q.
> > > > > (ii) Find the equation of L6 in terms of t.
> > > > >
> > > > > (c) A student wants to use a curve mirror to focus a
parallel
> > > > light
> > > > > beam to a fixed point. Explain whether he should use a
> circular
> > > > > mirror or a parabolic mirror.
> > > > >
> > > > >
> > > > > thx!
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