Help Geometry Question.. Please !!!!?

Question

use the given endpoint R and midpoint M of RS to find the coordinates of the other endpoints...

1. R (-3,-2) , M (-1, -8)

2. R (3,4) , M (3,-2)

3. R (11,-5), M ( -4,-4)

please help... i'll give 10 points for the best answer

Answer 1

we know,

M(x,y)= (sum of x coordinates of end pnts/2 , sum of ordinates/2)

  so,

for 1.

       -1=(-3+x)/2     &         -8=(-2+y)/2

     -2=-3+x                       -16=-2+y

      x=1                               y= -14

thus, for no.1., S(x,y)=(1,-14)

you mcan do the rest yourself now.

Answer 2

1.(1,-14)

2.(3,-8)

3.(-19,-3)

Answer 3

Multiply coordinates of M by 2 and subtract coordinates of R to get coordinates of S in EACH case.

e.g. in (1) S = (-2, -16) - (-3, -2) = (-2+3, -16+2) = (1, -14)  Now reapeat it for the rest.

Answer 4

To find a midpoint when you have 2 endpoints, you would first calculate the x coordinate, then you will calculate the y coordinate.  So the first formula to find X is:  x = [(x1 +x2)/2]

For problem 1, you already have the midpoint coordinates, so you could set up your formula to solve for x (for the other endpoint) this way:

-1 = [(-3+x)/2]

First step is multiplying both sides by 2 (or 2/1) to get rid of the denominator on your right side.  You are left with:

-2 = -3 + x

Simple math solves for x.  Add 3 to both sides to get x alone on the right.  You are left with 1 = x.  So there is your first coordinate for your endpoint S.  You do exactly the same thing to solve for the Y coordinate.

To start you off, your first answer will be S (1,-14).  

Answer 5

U knw (R+S)/2 =M ; so S wil b

(1) (1,-14)

(2) (3,-8)

(3)(-19, -3)

Answer 6

I believe you are learning the Formula for calculating the midpoint?

Midpoint = ( x1+x2 over 2, y1+y2 over 2)

You want to find point S(x2,y2), and you are given point R(x1,y1).

1. Base on the above we can get 2 equations.

(-3+x2)/2 = -1 and (-2+y2)/2 = -8

Now just solve for x2 and y2.

-3+x2 = -2

x2 = 1

-2+y2 = -16

y2 = -14

So point S is (1,-14).

Use the same idea for the the other questions. ^-^