19.1  b) integral ln x dx from 1 to e
      c) integral sqrt(1-x^2)/x^2 dx from 1/2 to 1
      d) integral x^3*cos(x/2) dx from 0 to pi
      e) integral e^x*sin x dx from 0 to pi
      f) integral x*(sin x) * (cos x) dx from -pi to pi	  
 
19.2  a) integral (3x^4+6x^2+1)/(x^2+1) dx from -1 to 1
      c) integral (x^3+1)/(x^3-x^2) dx from 2 to 4
      d) integral (x^3+x+2)/((x-1)(x+1)) dx from 2 to 3
      f) integral (x^3+1)/(x(x^2-1)) dx from 1 to 2

19.3  b) integral sin(x/2)/cos^2(x/2) dx from 0 to pi/2
      e) integral sqrt(cos  x - cos^3 x) dx from -pi/2 to pi/3
      f) integral (x+3)/(x^2+4) dx from 0 to 2
      f) integral x^x*(1 + ln x) dx from 1 to 3
      i) integral x^2*arctan x dx from 0 to 1