Question 17 (5 points)

Find the distance between the points [tex]\((9, -6)\)[/tex] and [tex]\((-4, 7)\)[/tex].

A. [tex]\(3 \sqrt{39}\)[/tex]

B. [tex]\(2 \sqrt{85}\)[/tex]

C. [tex]\(3 \sqrt{39}\)[/tex]

D. [tex]\(13 \sqrt{2}\)[/tex]



Answer :

To find the distance between the points [tex]\((9, -6)\)[/tex] and [tex]\((-4, 7)\)[/tex], we use the distance formula. The distance formula for two points [tex]\((x_1, y_1)\)[/tex] and [tex]\((x_2, y_2)\)[/tex] is:

[tex]\[ \text{Distance} = \sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2} \][/tex]

Here, the coordinates of the first point [tex]\( (x_1, y_1) \)[/tex] are [tex]\( (9, -6) \)[/tex] and the coordinates of the second point [tex]\( (x_2, y_2) \)[/tex] are [tex]\( (-4, 7) \)[/tex].

Step-by-step, we calculate the differences in the coordinates:
[tex]\[ \Delta x = x_2 - x_1 = -4 - 9 = -13 \][/tex]
[tex]\[ \Delta y = y_2 - y_1 = 7 - (-6) = 7 + 6 = 13 \][/tex]

Next, we substitute [tex]\( \Delta x \)[/tex] and [tex]\( \Delta y \)[/tex] into the distance formula:
[tex]\[ \text{Distance} = \sqrt{(-13)^2 + (13)^2} \][/tex]

Calculating the squares of [tex]\( \Delta x \)[/tex] and [tex]\( \Delta y \)[/tex]:
[tex]\[ (-13)^2 = 169 \][/tex]
[tex]\[ (13)^2 = 169 \][/tex]

Adding these values together:
[tex]\[ 169 + 169 = 338 \][/tex]

Finally, taking the square root of the sum:
[tex]\[ \sqrt{338} \][/tex]

We can simplify this radical:
[tex]\[ 338 = 2 \times 169 = 2 \times 13^2 \][/tex]
[tex]\[ \sqrt{338} = \sqrt{2} \times 13 = 13\sqrt{2} \][/tex]

Thus, the distance between the points [tex]\( (9, -6) \)[/tex] and [tex]\( (-4, 7) \)[/tex] is:
[tex]\[ 13\sqrt{2} \][/tex]

So the correct answer is:
[tex]\[ \boxed{D) \, 13\sqrt{2}} \][/tex]