Answer: not orthogonal
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Step-by-step explanation:
We compute the dot product. This is where we multiply corresponding coordinates and add the products.
If
u = (a,b,c)
v = (d,e,f)
then
u dot v = a*d + b*e + c*f
If the result of the dot product is zero, then the vectors are orthogonal.
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So,
u dot v = a*d + b*e + c*f
u dot v = -1*2 + 3*(-1) + (-1)*5
u dot v = -2-3-5
u dot v = -10
The result is nonzero.
It tells us that these vectors are not orthogonal.
The two vectors do not form a 90 degree angle.