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# Calc BC help!

Registered User Posts: 166 Junior Member
edited April 2009
In the paper 2007, question 3, part (a), I don't understand the solution at all. I'm confused about the areas of polar curves, and prep books aren't helping. (i'm self study...)
Post edited by starwarsfan on

## Replies to: Calc BC help!

• Registered User Posts: 166 Junior Member
also, does anyone know what the curve for calc bc is? what's the % for a 5?
• Registered User Posts: 676 Member

AP Calculus BC
AP Examinations - May 2008

5 - 30,045 students or 43.5%
4 - 12,008 students or 17.4%
3 - 13,408 students or 19.4%
2 - 4,664 students or 6.7%
1 - 8,978 students or 13.0%
Number of Students: 69,103

You can also find the grade distributions for other subjects by going here: http://www.collegeboard.com/student/testing/ap/subjects.html. Click on the subject and on the left-hand side, click on 'Grade Distribution'.
• Registered User Posts: 2,303 Senior Member
^i think he meant the curve..

i think BC curve shouldn't be too diff from AB's curve,

probably 60~65+ pts would be the cutoff for 5?

OT
i'd like to know this as well..i suck at polar curves and series~~
where's themathprof? hehe
• Registered User Posts: 810 Member
I usually dodge the BC questions, as I only teach AB and have long since forgotten half of the BC material. Such as polar curves. :)

That being said, here's my understanding of it, taking a quickie glance at what's there:

Let @ = theta. If you wanted to calculate the area of the shaded region, the integral expression represents only the area of the section of the curve from @ = 2pi/3 to @ = 4pi/3. In order to understand what's going on there, imagine a straight line connecting the origin to each of the intersection points. That divides the region into two sections: (1) a Pac-man like section consisting of the circle (r = 2) from @ = 2pi/3 traced around clockwise to the other intersection point at @ = 4pi/3, and (2) the rest of the shaded region that's sitting in "Pac-man's mouth".

The integral calculates the area of what's in Pac-man's mouth. The other piece (the 2/3pi(2)^2) of the area calculation is just finding the fraction of the circle that's there. In this case, there's 2/3rds of the circle there (an entire circle encompasses 2pi, and this circle encompasses 4pi/3: 2pi/3 from @ = 0 to @ = 2pi/3, and 2pi/3 from @ = 4pi/3 back to @ = 2pi).

Hope that helps.
• Registered User Posts: 2,303 Senior Member
^thanks, though i got lost half way lol.. kinda sleep right now.. i'll bookmark this and come back later :)
• Registered User Posts: 2,303 Senior Member
also, this guy has really neat, easily understood notes for calculus..
Pauls Online Notes : Calculus II - Area with Polar Coordinates
^there he explains the polar curves etc..
its pretty useful~
• Registered User Posts: 2,303 Senior Member
I nailed the polar section. yay..

its pretty easy now cuz i know how the limits sweep counterclockwise etc
• - Posts: 16,060 Senior Member
The curve for BC I believe hovers around 65/108. 75 is a safe 5 (in that it will almost always be a 5 even if barely). Above 90/108 and you've pretty much aced the test.

FWIW, I found PR to be very helpful. You'll get a good feeling for what's on the test and its explanations are quite good too.
• Registered User Posts: 2,303 Senior Member
^ty, i have the pr book, and willl start atking them soon :)
This discussion has been closed.