The angle between the vectors t and u is 45°. And the vector t and vector w are orthogonal to each other.
<h3>What is a vector?</h3>
The quantity which has magnitude, direction and follows the law of vector addition is called a vector.
The vectors are given below.
t = −5i + 2j, u = −3i + 7j, and v = 8i + 20j
Part A: Then the angle between vectors t and u will be

Then we have
cos θ = [(−5i + 2j)(−3i + 7j)] / [√{(-5²) + 2²} + √{(-3)² + 7²}]
cos θ = 1 / √2
θ = 45°
Part B: c is a scalar
If
, then 
Let c = 2, then we have

Part C: Use the dot product to determine if t and w are parallel or orthogonal.

More about the vector link is given below.
brainly.com/question/13188123
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