Step-by-step explanation:
the distance can be seen as Hypotenuse of a right-angled triangle with its legs being the x and y coordinate differences.
so, we use Pythagoras
c² = a² + b²
with c being the Hypotenuse (the side opposite of the 90 degree angle).
distance² = (-10 - -3)² + (-9 - 8)² = (-7)² + (-17)² = 49+289 =
= 338
distance = sqrt(338) = sqrt(2×169) = 13×sqrt(2) =
= 18.38477631...
