## Finding the gradient of a curve without the equation

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Spen
Posts: 70
Joined: Sat Sep 12, 2009 8:28 pm UTC

### Finding the gradient of a curve without the equation

This is for a chemistry exam I've got on monday, I know that I'll need to find the tangent to the curve (if this even comes up), the only method I can remember having been taught to do this is to use a plane mirror until the curve is completely symmetrical at the point which you need the gradient of, draw a line along the base of the mirror to give the normal and use a set square to draw the tangent to the curve. One problem with this: I can't find a mirror that I'll be able to take into an exam ANYWHERE, so is there a method to do this accurately without the mirror?
Yes, I have made use of google but I can only find stuff on differentiation, if there is no way to do it without a mirror I might be able to get a hold of one tomorrow if I'm lucky.
Spen

achan1058
Posts: 1783
Joined: Sun Nov 30, 2008 9:50 pm UTC

### Re: Finding the gradient of a curve without the equation

Approximate with a ruler. Preferably one with clear plastic. If they don't give you the equation, they don't expect you to be too accurate.

Spen
Posts: 70
Joined: Sat Sep 12, 2009 8:28 pm UTC

### Re: Finding the gradient of a curve without the equation

Ok then, just that in the physics practical they didn't but do expect you to be accurate (hence knowing the mirror technique), if it comes up it'll only be a couple of marks anyway.
Thanks

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