Diketahui vektor a=6i+4j-2k dan vektor b=4i-rj+k kedua vektor saling tegak lurus,nilai r adalah

a = (6,4,-2)
b = (4,-r,1)

a • b = 0
(6 × 4) + (4 × -r) + (-2 × 1) = 0
24 - 4r -2 = 0
22 - 4r = 0
22 = 4r
11/2 = r