2008 X2 HSC paper (1 Viewer)

[school4nerds]

with question 5. C) ii) could someone explain how you find the area of the cross section the way the worked answers do?

i thought it wouldve been h(x2- x1) (assuming x1 and x2 was a rectangle so base x height)

 

[mraznboy]

the cross section is not a rectangle - you are finding the area of a torus A=pi(R^2 - r^2)