Caculate the distance between the points l= (-1 ,-2) and (7,-9)

Point 1 (-1, -2) and point 2 (7, -9), x1= -1, y1= -2, x2= 7 and y2= -9  
we will calculate distance with next formula :   
L^2= (x2 - x1)^2 + (y2 - y1)^2 =>  L^2 = (7- (-1))^2 + (-9-(-2))^2 =>
L^2 = (7+1)^2 + (-9+2)^2  => L^2 = 8^2 + (-7)^2   => L^2 = 64 + 49 =>
L^2 = 113 =. L= square root of 113 =>  L= 10.63

Using the rise/run rule. you would get 2/6.simp. 1/3