Cartesian Coordinates

Cartesian Coordinates are read from the origin (0,0).

They are in order of x-coordinate (horizontal) and y-coordinate (vertical).

Example One - Brain X-Ray in One Quadrant

Scan of a slice of human brain

In brain surgery, accuracy is important. In this brain x-ray, the coordinates of brain parts are:

hypothalamus ( 10 , 3.2 )
optic chiasma ( 11 , 3.2 )
pituitary gland ( 11 , 2.4 )

Example Two - Pregnant Woman's X-Ray in Four Quadrants

X-Ray image of a pregnant woman

This is an x-ray of a pregnant woman with a baby in her womb. The x-axis goes across her lower belly where the surgeon will perform a Caesarean section to give birth to the baby. The y-axis is the woman's backbone. The coordinates of points are:

baby's eye at A = ( 1 , 4.8 )
top of woman's hip at C = ( 4 , –1.2 )

Question - Pregnant Woman's X-Ray

In the Cartesian plane of the pregnant woman's x-ray above, write the coordinates of the:

back of the baby's head at B
top baby's hip at D.

Answers
B = ( 3.7 , 1.7 )
D = ( –5 , 6.7 )

Did You Know That...?

Cartesian planes are named after 17th century French mathematician and philosopher Rene Descartes whose writings were prohibited by the Roman Catholic Pope. His famous line was "I think, therefore I am". In Latin, this is "Cogito ergo sum".