 
Summary: 10.3 Polar coordinates
Coordinate Systems
· Coordinate system: just a way to define a point.
· Rectangular Coordinate System consists two perpendicular lines, called
axes, and an origin.
Each point P in a plane can be associated with a pair of rectangular
coordinates( , )x y , where x is the distance from origin to the foot of the
perpendicular from P on the Xaxis and y is the distance from origin to the
foot of the perpendicular from P on Yaxis.
P(x,y)
x
y
start at origin
move `x' units horizontally
and `y' units vertically and
we reach point `P'
· Another way to define the point P in the plane by a pair of coordinates ( , )r
called polar coordinates.
· A polar coordinate system consists a fixed point O, called the pole or
origin, and a ray starting from the pole, called the polar axis.
