Question

Punkt S jest środkiem odcinka AB. Oblicz jakie współrzędne ma punkt B gdy :

S = ( -1, 5 ) , A = ( -10, 7 ).

Answer 1

Odpowiedź:

A = (- 10 , 7 ) , S = (- 1 , 5 ) , B = (xb , yb)

xa = - 10 , xs = - 1 , ya = 7 , ys = 5

xs = (xa + xb)/2

2 * xs = xa + xb

xb = 2 * xs - xa = 2 * (- 1) - (- 10) = - 2 + 10 = 8

ys = (ya + yb)/2

2 * ys = ya + yb

yb = 2 * ys - ya = 2 * 5 - 7 = 10 - 7 = 3

B = ( 8 , 3 )

Answer 2

-10+x/2 = -1
2* -10+x/2 = 2*(-1)
-10+x = -2
x = -2+10
x = 8

7+y/2 = 5
2* 7+y/2 = 2*5
7+y = 10
y = 10-7
y = 3

B = (8,3)