TICALCS.net

When i do (PI)(Integral)( ROT(r^2-x^2),x,-r,r) I get (r*|r|*(PI)^2)/2

but aint this supposed to be 3/4(PI)r^2? or is the TI89 too advanced, and gives a more correct answer?

thanks on advance

Since noone seems to know why, could anyone try this on their calculator so that i will know if it is only mine, or all TI89s