Answer:
A
Step-by-step explanation:
Distance between 2 points
[tex] = \sqrt{(x1 - x2)^{2} + (y1 - y2)^{2} } [/tex]
☆ (x₁, y₁) is the first coordinate while (x₂, y₂) I'd the second coordinate.
Length of RS
[tex] = \sqrt{ {[ - 1 -( - 4)] }^{2} + (9 - 1)^{2} } \\ = \sqrt{( - 1 + 4)^{2} + 8^{2} } \\ = \sqrt{ {3}^{2} + 64 } \\ = \sqrt{73} \\ = 8.54 \: (3 \: s.f.)[/tex]
Thus, RS is about 8.5 units.
