Answer :
To find the angle between two vectors, you can use the dot product formula:
θ = arccos((u ⋅ v) / (||u|| × ||v||))
where u and v are the two vectors, ||u|| and ||v|| are the magnitudes of the vectors u and v, and ⋅ is the dot product.
In the first problem, you are given that u = 2i - 3j and v = 3i + 8j. To find the angle between these vectors, you can first find the dot product of u and v:
u ⋅ v = (2i - 3j) ⋅ (3i + 8j)
= (23) + (-38)
= 6 - 24
= -18
Next, you can find the magnitudes of u and v:
||u|| = √((22) + (-3-3)) = √(13)
||v|| = √((33) + (88)) = √(73)
Now you can use the dot product formula to find the angle between the vectors:
θ = arccos((-18) / (√(13) × √(73)))
= arccos(-18 / 961)
You can use a calculator to find the value of arccos(-18 / 961), which is approximately 125.75 degrees.
In the second problem, you are given that u = <2, -5, 3> and v = <5, 7, -9>. To find the angle between these vectors, you can follow the same process as before:
u ⋅ v = (25) + (-57) + (3×-9) = 10 - 35 - 27 = -52
||u|| = √((22) + (-5-5) + (33)) = √(34)
||v|| = √((55) + (77) + (-9-9)) = √(109)
θ = arccos((-52) / (√(34) × √(109)))
= arccos(-52 / 3706)
You can use a calculator to find the value of arccos(-52 / 3706), which is approximately 179.42 degrees.
So the answer to the first problem is 125.75 degrees, and the answer to the second problem is 179.42 degrees.
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