What is the distance between the points (-6,4)(9,12

Question

What is the distance

 

Answer 1

To solve this problem we need to know the distance formula between two points P(x1, y1) and Q(x2, y2).

 

d = sqrt( (x2 - x1)^2 + (y2 - y1)^2 )

 

Plugging in given values we have

 

d = sqrt( (9 - (-6) )^2 + (12 - 4)^2 )

d = sqrt( 15^2 + 8^2 )

d = sqrt( 225 + 64 )

d = sqrt( 289 )

d = 17

 

A common mistake made is when the one or both of the  second coordinates is negative.  Students mistake the negative of the coordinate with that of the formula.  For example instead of using 9 - (-6) they use 9 - 6.