Answer:
Obtuse.
Step-by-step explanation:
If we have a vector v = (a, b, c)
The magnitude of the vector is:
|v| = √(a^2 + b^2 + c^2)
And the dot product of two vectors:
v = (a, b, c)
w = (c, d, e)
is:
v.w = |v|*|w|*cos(θ) = a*c + b*d + c*e
With that relation, we can find the angle between the two vectors.
In this case, we have:
v = ⟨−1,0,1⟩
then:
|v| = √( (-1)^2 + 0^2 + 1^2) = √2
And:
w = ⟨4,5,2⟩
then:
|w| = √( 4^2 + 5^2 +2^2) = √116
Then:
v.w = (√2)*(√116)*cos(θ) = (-1)*(4) + 0*5 + 1*2
(√2)*(√116)*cos(θ) = -4 + 2 = -2
(15.23)*cos(θ) = -2
cos(θ) = -2/15.23
θ = Acos( -2/15.23) = 97.5°
Then the angle is larger than 90°, so the angle is obtuse.
