If a= (4,-5) and b= (7,-9) what is the length of side ab

The length of side AB is 5 units

Step-by-step explanation:

* Lets revise how to find the distance between two points

- If there are two points their coordinates are (x1 , y1) and (x2 , y2),

 then we can find the distance between them by this rule:

 d = √[(x2 - x1)² + (y2 - y1)²]

- Now lets solve the problem

∵ A = (4 , -5)

∵ B = (7 , -9)

- To find the length of AB use the rule of the distance above

- Let point A is (x1 , y1) and point B is (x2 , y2)

∵ x1 = 4 and x2 = 7

∵ y1 = -5 and y2 = -9

∴ AB = √[(7 - 4)² + (-9 - -5)²]

∴ AB = √[(3)² + (-4)²]

∴ AB = √[9 + 16] = √25 = 5

* The length of side AB is 5 units