Section 12.6 – Area and Arclength in Polar Coordinates 12.2
Integrals in Polar Coordinates Area of a Polar Curve: These are needed to make some integration possible.
The total area of the region enclosed NO CALCULATOR by the polar graph of is
NO CALCULATOR Not an option. Let’s check the graph. Symmetric about the x-axis. So...
CALCULATOR REQUIRED The area of the region enclosed by the graph of the polar curve is 4.712 9.424 18.849 37.699 75.398
CALCULATOR REQUIRED The approximate total area of the region enclosed by the polar graph of is: 0.393 0.785 1.178 1.571 1.873
Find the area inside . It’s a circle! Using calculus: Wait! What?!? The circle actually gets drawn twice. We need to change our limits of integration. Better.
CALCULATOR REQUIRED Set up to definite integral to find the area inside the smaller loop of
Or we could restrict it to exclude the loop. If would have wanted the total area, we would have to change things a bit. Total Area. Inner Loop. Without the loop. We could take the whole area and subtract the inner loop (no double counting). Or we could restrict it to exclude the loop.
CALCULATOR REQUIRED Find the area inside What?!? Let’s try another way.
NO CALCULATOR: Find the area of the region inside the circle r = 4 and outside
We’ll need to subtract red from blue. =7.653
=0.571 We’ll need to add red and blue because they make up two halves. However, the angle ranges are different for the two functions. =0.571
Length of an Arc in Polar Coordinates
CALCULATOR REQUIRED
NO CALCULATOR