Year 12s: what will be the first way you research your future options? >>

If sin y = 2sin x show that (dy/dx) squared =

If sin y = 2sin x show that (dy/dx) squared = 1 +3sec^2 y

read as 1 + 3 (sec squared y)

note: (dy/dx) squared . ... so only have to differentiate once and square : don've to differentiate twice!

so fare I have dy/dx = -2(cos x/cos y)

Am I doing this write? have to change cos x to a y .... but don't know which identity to use. then square both sides ?

Reply 1

luddite

can someone move this to maths as oppose to maths exams thanks

Reply 2

A Slice of Pi

This is a relatively straightforward problem if you are familiar with implicit differentiation. If you're not, I would recommend viewing the tutorial videos at http://www.m4ths.com/ and having another attempt. If you are still stuck, here's my answer:

Spoiler

Reply 3

tiny hobbit

Original post by A Slice of Pi

Spoiler

I've spent much of the last 18 hours or so giving hints of the way forward to this student, rather than giving the solutions to the problem sheet that s/he is tackling. Please could you do the same.

Reply 4

A Slice of Pi

Original post by tiny hobbit

I've spent much of the last 18 hours or so giving hints of the way forward to this student, rather than giving the solutions to the problem sheet that s/he is tackling. Please could you do the same.

And that is precisely the reason why the solution was hidden.

Reply 5

luddite

Original post by tiny hobbit

I've spent much of the last 18 hours or so giving hints of the way forward to this student, rather than giving the solutions to the problem sheet that s/he is tackling. Please could you do the same.

I (eventually) did the solution ...you can see from the other thread (i posted in the wrong forum)

the above poster wrote his post about an hour after i had tried completing it with the hints and tips :smile: