diketahui koordinat titik p(a -2 3) q(0,4,5), dan r(2,5,c).jika vektor pq tegak lurus dengan vektor qr,hasil a-c=...

p(a -2 3)
q(0 4 5)
r(2 5 c)
...
pq = [0 4 5] - [a -2 3] = [-a 6 2]
qr = [2 5 c] - [0 4 5] = [2 1 c-5]
..
pq T qr = 0
[-a 6 2] × [2 1 c-5] = 0
-2a + 6 + 2(c-5) = 0
-2a + 6 + 2c - 10 = 0
-2a + 2c -4 = 0
-2(a - c) = 4
a - c = -2

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