The graph shows where four friends' houses are located. how many units is it between brian's house and sue's house? −11 units −9 units 9 units 11 units a coordinate plane with x axis ranging from negative 10 to 10 and y axis ranging from negative 10 to 10. the point begin ordered pair negative 7 comma 9 end ordered pair labeled brians house comma the point begin ordered pair negative 7 comma negative 2 end ordered pair labeled sues house comma the point begin ordered pair 4 comma 6 end ordered pair labeled lindas house comma and the point begin ordered pair 1 comma negative 5 end ordered pair labeled elliots house.

Given

Brian's house: (-7, 9)

Sue's house: (-7, -2)

Find

The number of units between Brian's house and Sue's house.

Solution

Both Brian and Sue live on the "street" x=-7, so the distance between their houses is the distance between -2 on that street and +9 on that street. We always consider distance to be positive, so it doesn't matter whether we start at Brian's house and go -11 units to Sue's house, or start at Sue's house and go +11 units to Brian's house. Either way, we travel 11 units.

"Displacement" is another matter. That has a sign associated with it and there is always a reference direction that is positive. Movement in the opposite direction results in a negative displacement. "Distance" is always positive.