A Level Maths Notes: FP1 – Finding the Area Between Two Curves Written in Polar Coordinates
Problems of this kind are variable and each one may demand a different approach.
In the diagram below
is
the curve
and
is
the curve
W
e have to find the shaded are and this must be done in several
stages.
We find the points A and B of intersection of the two curves,
specifically, we find the
values
and
Having
found these, the shaded area will consist of the sum of two
integrals:
We integrate for
the
cardioid between
and
and
for
between
and
Notice that
is
negative.
The pints of intersections are the solutions to![]()
For
we
integrate between
and
or
anticlockwise from
![]()
![]()
The area of the circle between A and B is![]()
The shaded area is the sum of these![]()