Area under the curve in PV diagram

[jack1234]

Area under the curve in PV diagram(q35)

For this question:
http://tinyurl.com/37tqvp

What I do is to find the area of PV under the straight line, using
(area of bigger rectangle-area of smaller rectangle)/2
=((p2*v2)-(p1*v1))/2

but this is not one of the choices.

May I know how to solve this question correctly?

 

[Astronuc]

What I do is to find the area of PV under the straight line, using (area of bigger rectangle-area of smaller rectangle)/2
=((p2*v2)-(p1*v1))/2

This is an incorrect interpretation of the graph.

The process takes the gas from (V1, P1) to (V2, P2) along the diagnonal line. The work is the area under that diagonal line, and not the area difference of the two boxes. One needs to find the area of the trapezoid between the diagonal line (V1, P1) to (V2, P2) and the abscissa.

 

[jack1234]

Got it right, thanks:)