Question

Jika titik P (2,-3) dicerminkan terhadap garis lurus K menghasilkan bayangan P' (4,5) maka persamaan garis lurus K adalah...

Answer 1

Garis melalui PP' -->  (y+3)/(5+3) = (x-2)/(4-2)
2(y+3) = 8(x-2)
2y + 6 = 8x - 16
2y = 8x - 22
y = 4x - 11
4x - y = 11

misal R titik tengah PP'
R = 1/2 {(2, -3) + (4, 5)}
Rx = 1/2 (2+4) = 3
Ry = 1/2(-3+5) = 1

garis lurus K = garis tegak lurus 4x-y = 11 melalui R(3,1)
x + 4y = 1(3) + 4(1)
x + 4y = 7
garis k --> x + 4y - 7 = 0