Try graphing this on the TI-89.
To find the slope of a polar curve: We use the product rule here.
To find the slope of a polar curve:
Example:
Area Inside a Polar Graph: The length of an arc (in a circle) is given by r . q when q is given in radians. For a very small q, the curve could be approximated by a straight line and the area could be found using the triangle formula:
We can use this to find the area inside a polar graph.
Example: Find the area enclosed by:
Notes: To find the area between curves, subtract: Just like finding the areas between Cartesian curves, establish limits of integration where the curves cross.
When finding area, negative values of r cancel out: Area of one leaf times 4: Area of four leaves:
To find the length of a curve: Remember: For polar graphs: If we find derivatives and plug them into the formula, we (eventually) get: So:
There is also a surface area equation similar to the others we are already familiar with: When rotated about the x-axis: p