How do you find the area enclosed by y=sin xy=sinx and the x-axis for 0≤x≤pi0xπ and the volume of the solid of revolution, when this area is rotated about the x axis?

1 Answer
May 4, 2016

Area = 2 areal units.
Volume of the solid of revolution = pi^2/2π22 cubic units.

Explanation:

Area = intydx=intsin x dxydx=sinxdx, between the limits x=0 and x=pix=0andx=π

= [- cos x ][cosx], between the limits

= [ - cos pi + cos 0 ] = [ 1 + 1 ] = 2=[cosπ+cos0]=[1+1]=2 areal units.

Volume = piint y^2dx= pi int sin^2 x dxπy2dx=πsin2xdx, between the limits x=0 and x=pix=0andx=π

=pi/2int (1-cos 2x)dx=π2(1cos2x)dx, between the limits x=0 and x=pix=0andx=π

= pi/2[x- (sin 2x)/2 ]=π2[xsin2x2], between the limits

=pi/2 [ (pi-0)- (0-0) ] = pi^2/2=π2[(π0)(00)]=π22 cubic units/