Calculus help with reimann sum?

Question

Take the reimann sum for f(x) from 0 to 3 with 6 terms using right endpoints.
would that be .5(f(.5)+f(1)+f(1.5)+f(2)+f(2.5)+f(3))
the equation is x-4sin(2x) and i figured the answer to be 4.517743(it should be to six decimal places) but that answer is wrong!! help please

.5(f(.5)+f(1)+f(1.5)+f(2)+f(2)+f(2.5)+f(3))
don't know why it cut that off

+f(2.5)+f(3))
****

Answer 1

Yes, beware of using degree. Degree is an unit for geometric angle measurements, while radian is a ratio, i.e. a number. Just as % = 1/100, consider a sector within a circle, radian = (arc length)/radius. Since radius is constant in any sector of a circle, and arc length corresponds to the angle of the sector, radian is usually explained as an measurement of this angle.

If x is in degree, you are adding a value in degree unit, x, to a ratio, 4sin(2x), which is technically wrong. Just like adding 1 inch to 1 kg.
Thus, in expression like this, using degree is wrong.

Answer 2

I don't see anything wrong with the way you've got it set up. My guess is that you've got a 'finger fumble' somewhere in your calculations. Or that you have the angular mode on your calculator set to degrees instead of radians (or radians instead of degrees). Try it both ways and see if that helps.


Doug

Answer 3

This should be done in radian mode...NOT IN DEGREE MODE.

One rule, which is not so obvious...everything which you will learn in calculus ONLY works for radians. If you ever get anything in degrees, convert them to radians and then do whatever you need to do.

Answer 4

oh hold on let me ask my chinese friend ............................. he says ur ****** up and u should get a life while ur boy/girl friend is getting ramed