Lulu marks the points (9,2) and (3,6) on the coordinate plane. What is the distance between these two points, rounded to the nearest tenth of a unit?

A. 6.0 units
B. 10.0 units
C. 7.8 units
D. 7.2 units

1 answer

To find the distance between the points \((9, 2)\) and \((3, 6)\), we can use the distance formula:

\[ d = \sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2} \]

Here, \((x_1, y_1) = (9, 2)\) and \((x_2, y_2) = (3, 6)\).

Substituting the coordinates into the formula:

\[ d = \sqrt{(3 - 9)^2 + (6 - 2)^2} \]

Calculating the differences:

\[ 3 - 9 = -6 \implies (-6)^2 = 36 \] \[ 6 - 2 = 4 \implies 4^2 = 16 \]

Now substituting these values back into the distance formula:

\[ d = \sqrt{36 + 16} = \sqrt{52} \]

Now, we need to simplify \(\sqrt{52}\). We can factor it:

\[ \sqrt{52} = \sqrt{4 \times 13} = \sqrt{4} \times \sqrt{13} = 2\sqrt{13} \]

To find the numerical value of \(2\sqrt{13}\), we first approximate \(\sqrt{13}\):

\(\sqrt{13} \approx 3.60555\), so:

\[ 2\sqrt{13} \approx 2 \times 3.60555 \approx 7.2111 \]

Rounding to the nearest tenth, we get:

\[ 7.2 \]

Thus, the distance between the two points, rounded to the nearest tenth of a unit, is:

\[ \boxed{7.2} \text{ units} \]