diketahui A (4,7,0), B(6,10,-6) dan C (x,9,0) agar sudut BAC =90° , maka nilai x adalah

BAC = 90° ==> AB tegak lurus AC

AB = B-A = (6,10,-6) - (4,7,0) = (2, 3, -6)
AC = C-A = (x,9,0) - (4,7,0) = (x-4 , 2, 0)

AB•AC = 0
(2, 3, -6)•(x-4, 2, 0) = 0
2(x-4) + 3×2 + (-6)×0 = 0
2x - 8 + 6 = 0
2x - 2 = 0
2x = 2
x = 1

smg mmbantu