help with this math equation?

Question

okay, im suppose to pick a side of a polygon and i choose, AB, which A=(0,-5) and B=(8,9), how am i suppose to write an equation for the line of this side?

help is really appreciated. thanks..

sRY if there's any confusions, but i dont know how to do it,, i need an equation for that side,, thanks

no i dont think is the slope,,, heres the exact words for my math hw,,"Select a side of your polygon. Write the equation of the line for this side". So i picked the side AB,, but i dont know what to do afterwards,, thanks

Answer 1

Use the standard equation for a line going through two points.

I.e. for two points (x1,y1), (x2,y2) the equation is :
(y2-y1)/(x2-x1) = (y-y1)/(x-x1).

In this case we have (x1,y1)=(0,-5) and (x2,y2)=(8,9), so
(9-(-5))/(8-0) = (y-(-5))/(x-0)
which computes to
14/8 = (y+5)/x
or, in standard format
y = (7/4)*x - 5

If you now check (fill in those two points) you will see it is the correct equation for both.

Hope this helps :-)

Answer 2

x = a y + b

(0, -5) => 0 = -5 a + b
<1> => b = 5 a

(8, 9) => 8 = 9 a + b
using <1> => 8 = 9 a + 5 a
=> 8 = 14 a
=> a = 8 / 14
<2> => a = 4 / 7

using <1> and <2> => b = 5 (4 / 7)
=> b = 20 / 7

Therefore the equation is:
x = (4 / 7) y + (20 / 7)
or:
7 x = 4 y + 20

Answer 3

make it a triangle, I assume that you know the pythagorean theorm. subtract the larger x coordinate from the smaller one. (8-0=8). THen do the same for the y coordinate (9--5=9+5=14) then square them both 8^2 is 64 and 14^2 is 196. Then add them both, 196+64=260, then take the square root 16.12545.

In higher level math you can do radicals and it becomes 2 squareroot 65


EDIT: so you're looking for slope?

Answer 4

ΔY/ΔX = (9 - -5)/(8 - 0) = 1.75

Y = 1.75 X + A
Plug in any of the numbers and you'll get A = -5

Y = 1.75 X - 5

Answer 5

Are you looking for an EQUATION for the LINE connecting those two points?

Or are you looking for a CALCULATION of the DISTANCE between those two points?

Answer 6

feanor's equation is correct good luck!