If A=(4,-5) and B=(7,9), what is the length of AB

 

   If A=(4,-5) and B=(7,9), what is the length of AB     

 

   It would help if you would sketch it on a coordinate grid.     

   Think of the line AB as the hypotenuse of a right triangle.     

 

    AB²  =  (x component)² + (y component)²     

    AB²  =         (7 – 4)²       +      (9 – (–5))²     

    AB²  =  3² + 14²  =  9 + 196  =  205     

    AB    =  sqrt (205)  =  14.32 (rounded)     

   _.