tolong bantuin ya pake cara ya

jawab

a =(x, -1, 5)
b = (6, -3, 6)

panjang proyeksi a pada b =  c = 5

c =  a.b / |b|

5 = (6x + 3 + 30) / √(6² +(-3)² + 6²)
5 = (6x + 33) / √81
5 = (6x + 33)/(9)

6x + 33= 45
6x = 12
x = 2

a = (2, -1, 5)
|a| = √(2² +(-1)² +(5)²)
|a| = √(4 +1 + 25)
|a| = √30