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I'm taking a high level Geometry course, and as it turns out, I'm a tad out of touch on at least one basic aspect learned years passed.

Parabola with equation [tex] y^2 = 2x[/tex], and parametric equation [tex] x = \frac{1}{2}t^2, y = t (t \in \Re) [/tex] etc.

The problem is concered with finding the equation of the chord that joins the distinct points P and Q on the parabola w/ parameters [tex] t_1 [/tex] and [tex] t_2 [/tex] respectively, etc.

No that much of that was relevant to my quandray, which is in finding the gradient of PQ.

[tex] m = \frac{t_1 - t_2}{{\frac{1}{2}(t_1^2 - t_2^2)} = \frac{2}{t_1 + t_2} [\tex]

edit: sorry, I guess I didn't get that tex tag right (what is wrong with it? Can I nest fractions like that?)

m = (t1 - t2)/[.5(t1^2 - t2^2)] = 2/(t1 + t2).

I can't remember (if I had learned it that is) how they arrived from the first to the latter fraction.

An explanation would be quite welcome, thanks.

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# Rusty - fill in missing steps, please

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