What rule is this? (1 Viewer)

[aussiechica]

what rule is this: y- y, = y. - y,
.................................. ----------
...................................... X. - x, (x- x, )

pretend the commas , are little 1s
and te full stops . are little 2s

What is its name and what is it used for and is there an alternative formula

Thankyou

 

[iambored]

do u mean

y.-y, y - y,
___ = ______ ?
x.-x, x - x.

the one i have just typed is the two point formula. used to find the equation of aline when u have 2 points. u can just find the gradient and then use the y-y, = m(x-x,)

basically, the long one is just a rearrangement of the other one, replacing m with the formula for finding the gradient when u have 2 points

 

[aussiechica]

Ive never heard of/cannot remember that formula, but I know you are right (its from an excel book, and it fits the following questions

Thanks!!

 

[:: ck ::]

its coordinate geometry

y-y1 = m(x-x1) is point gradient formula

or u can sub m = (y2-y1)/(x2-x1) to get 2 point formula

 

[iambored]

yeah, and no prob