Select the correct answer.

Vector [tex]u[/tex] has its initial point at [tex](15,22)[/tex] and its terminal point at [tex](5,-4)[/tex]. Vector [tex]v[/tex] points in a direction opposite that of [tex]u[/tex], and its magnitude is twice the magnitude of [tex]u[/tex]. What is the component form of [tex]v[/tex]?

A. [tex]v=\langle-20,36\rangle[/tex]
B. [tex]v=\langle-20,52\rangle[/tex]
C. [tex]v=\langle 20,36\rangle[/tex]
D. [tex]v=\langle 20,52\rangle[/tex]



Answer :

Let's solve the question step by step.

1. Find the components of vector [tex]\( u \)[/tex]:
The initial point of [tex]\( u \)[/tex] is [tex]\( (15, 22) \)[/tex], and the terminal point is [tex]\( (5, -4) \)[/tex]. To find the component form of vector [tex]\( u \)[/tex], we subtract the coordinates of the initial point from the coordinates of the terminal point:
[tex]\[ u_x = 5 - 15 = -10 \][/tex]
[tex]\[ u_y = -4 - 22 = -26 \][/tex]
Therefore, the component form of vector [tex]\( u \)[/tex] is:
[tex]\[ u = \langle -10, -26 \rangle \][/tex]

2. Determine the magnitude of vector [tex]\( u \)[/tex]:
The magnitude of vector [tex]\( u \)[/tex] is given by the formula:
[tex]\[ |u| = \sqrt{(u_x)^2 + (u_y)^2} \][/tex]
Plugging in the components of [tex]\( u \)[/tex]:
[tex]\[ |u| = \sqrt{(-10)^2 + (-26)^2} = \sqrt{100 + 676} = \sqrt{776} \approx 27.85677655436824 \][/tex]

3. Find the components of vector [tex]\( v \)[/tex]:
Vector [tex]\( v \)[/tex] points in the direction opposite to vector [tex]\( u \)[/tex], and its magnitude is twice that of [tex]\( u \)[/tex]. Since [tex]\( v \)[/tex] points in the opposite direction, we need to negate the components of [tex]\( u \)[/tex] and multiply by 2:
[tex]\[ v_x = -2 \times (-10) = 20 \][/tex]
[tex]\[ v_y = -2 \times (-26) = 52 \][/tex]
Therefore, the component form of vector [tex]\( v \)[/tex] is:
[tex]\[ v = \langle 20, 52 \rangle \][/tex]

The correct answer is:
[tex]\[ \boxed{\langle 20, 52 \rangle} \][/tex]

So, the correct answer is:
D. [tex]\( v = \langle 20, 52 \rangle \)[/tex].