This is about the finding the area formula. How do I get my a and b values for this equation: r = 4 +2cospheta

@hartnn

Question

This is about the finding the area formula. How do I get my a and b values for this equation: r = 4 +2cospheta

@hartnn

usukidoll · Answer

|dw:1349255706610:dw| area formula

hartnn · Answer

could u graph r=... ?

usukidoll · Answer

sure

usukidoll · Answer

|dw:1349255790689:dw|

usukidoll · Answer

How to get it manually WITHOUT wolfram. please ^^

hartnn · Answer

then u have to take values of pheta like , 0,45,90,...
and find the value of r for each, plot r.

usukidoll · Answer

oh ok. But.... hmmm...a = 0 and b = 2pi. How does that happen? Unless I plot phetas from 0 to 360 degrees

hartnn · Answer

because there is existence of that function in all 4 quadrants.
to get the area, we need to consider areas in all 4 quadrants,
so the antiderivative should start from 0 ,cover all 4 quadrants, and end to 2pi

usukidoll · Answer

ohhhhh yeah because of the circle. A piece of it is everywhere in the graph.

usukidoll · Answer

But what happens if it is a lemsicate cos2pheta would it mean that the area goes from 0 to pi/4 because a part of that leaf exists in one quadrant

hartnn · Answer

draw that lemniscate....and no, not 0 to pi/4

usukidoll · Answer

what the? I meant a piece of it

usukidoll · Answer

|dw:1349256555574:dw|