Draw an angle of 90 and divide it into four equal parts.
- first draw a 90 degree angle.
- then bisect the angle. now the value of each angle is 45 degrees and you have made 2 equal parts.
- then bisect both the 45 degree angles. Now the angles will each be of 22.5 degrees. now you have divided the 90 degree angle into 4 equal parts each of 22.5 degrees.