Tolong dikasih caranya sekalian ya :D terimakasih

OA = a = 2ki + (k + 1)j = (2k, k + 1)
OB = b = 4ki + (k + 5)j = (4k, k + 5)
a + b = (6k, 2k + 6)
T titik tengah AB
OT = t = (a + b)/2 = (6k, 2k + 6)/2 = (3k, k + 3)

OC = c = (10 + k)i = (10 + k, 0)

|CT| = |OT|
|t - c| = |t|
|(3k, k + 3) - (10 + k, 0)| = |(3k, k + 3)|
|(2k - 10, k + 3)| = |(3k, k + 3)|
√((2k - 10)^2 + (k + 3)^2) = √((3k)^2 + (k + 3)^2)
(2k - 10)^2 + (k + 3)^2 = (3k)^2 + (k + 3)^2
(2k - 10)^2 + (k + 3)^2 - (3k)^2 - (k + 3)^2 = 0
(2k - 10)^2 - (3k)^2 = 0
(2k - 10 + 3k)(2k - 10 - 3k) = 0
(5k - 10) (-k - 10) = 0
k = 10/5 = 2 atau k = 10/-1 = -10
Jadi k positif = k = 2