i missed class today because of a field trip, so i'm completely lost. if anyone could help explain how to do these that would be greatly appreciated! thank you. I don't need an answer, i just need to know how to set up summations

1.) use the Left Endpoint Rectangle Approximation Method to approximate the area

integral from 0 to 2 of x^3 dx

and the Right Endpoint Rectangle Approximation Method for the same problem

2.) integral from 1 to 4 of (x)^(1/2) dx using the trapezoidal rule, left endpt RAM, right endpt RAM, midpt RAM

3.) integral from 0 to pi of cosx dx

trapezoidal rule, left endpt RAM, right endpt RAM, and midpt RAM