program sumsin

 real sum, theta, tot
 integer i,n

 sum=0

 print '(a,$)',' Theta = '
 read(5,*) theta
 print '(a,$)',' N = '
 read(5,*)n

 do i=0,n
  sum = sum + sin(i*theta)
 end do

 tot = 0.5*cos(theta/2)/sin(theta/2)

 print '(a,e12.4)',' theta = ', theta
 print '(a,e12.4,a,e12.4)',' Sum = ', sum,'   total = ',tot

end