area

another quesn :
1. Let b not equal to 0 and for j = 0 , 1 , 2 , .........,n let Sj be the area of the region bounded by the y - axis and the curve xeay = sin by , j pi/b is less than equal to y is less than equal to (j+1) pi /b . Show that S0 , S1 , S2 , ........., Sn r in geometric progression . Also find their sum for a= -1 and b = pi.