On x-axis means the base take 4 an draw a semi-circle on the point 4 and make arc with the help of a compass and then draw a perpendicular to the arc point you have drawn and then take 1 cm from the base and it will be your perpendicular and then join the end point of 1 cm to the 0 and that will be your hypotenuse then from the perpendicular 1 cm draw an arc in the line x-axis  .and that is root 17.
      and do not forget to justify it.