Jika titik P (-2,3), Q (5,1) dan R tengah-tengah PQ. persamaan garis yang melalui R tegak lurus PQ adalah.. A. y+2x=1 B. 2x-y=-3 C. 2x+y=1 D. x-2y=-3 E. 3x+2y=-1
DB45
R tengah PQ = R = 1/2 (P+Q) Rx = 1/2 (px + qx) = 1/2 (-2+5) = 3/2 Ry = 1/2(py+qy) = 1/2(3+1) = 2 R(x,y) = R (3/2 , 2)
mPQ = (1-3)/(5+2) = -2/7 mR = -1/(mPQ) = 7/2
garis dengan m= 7/2 melalui R(3/2, 2) y - y1 = m(x -x1) y - 2 = 7/2 (x - 3/2) y - 2 = 7/2 x - 21/4 ... kalikan 4 4y - 8 = 14x - 21 4y = 14 x - 13 atau 14x - 4y - 13 = 0
R = 1/2 (P+Q)
Rx = 1/2 (px + qx) = 1/2 (-2+5) = 3/2
Ry = 1/2(py+qy) = 1/2(3+1) = 2
R(x,y) = R (3/2 , 2)
mPQ = (1-3)/(5+2) = -2/7
mR = -1/(mPQ) = 7/2
garis dengan m= 7/2 melalui R(3/2, 2)
y - y1 = m(x -x1)
y - 2 = 7/2 (x - 3/2)
y - 2 = 7/2 x - 21/4 ... kalikan 4
4y - 8 = 14x - 21
4y = 14 x - 13
atau
14x - 4y - 13 = 0