Answer:
n = 5
Step-by-step explanation:
0A = (1,3,-1) and OD=(-1,0,n)
AD = √ (-1-1)^2 + (0-3)^2 + (n-(-1))^2
7 = √ (-2)^2 + (-3)^2 + (n+1)^2
7 = √4 + 9 + (n+1)^2
Now squaring both sides we have :
7^2 = (√4 + 9 + (n+1)^2)^2
49 = 4 +9 + (n+1)^2
49 = 13 + (n+1)^2
49 -13 = (n+1)^2
36 = (n+1)^2
Taking the square root of both sides we have :
√36 = √(n+1)^2
6 = (n+1)
6 = n + 1
6 - 1 = n
5 = n
Therefore n = 5
