A 34.92 degree angle is the angle between the two equal sides of an
isosceles triangle which has the unequal side. 0.6 times the length of the
equal sides. It can be mathematically expressed as 2arcsin(0.30).
Illustrated below is a typical layout for a shot circle. Measure out from
the center of the circle with two tapes. Pull the two tapes tight and
separate them by 12 meters at the 20 meter mark on each tape. It will take
3 people and 3 tapes to do this. One person holds the two tapes which will
locate the sector lines in the center of the circle. The second person
pulls tight one of the sector line tapes and holds the zero mark of the
cross measuring tape at the 20 meter mark. The third person pulls tight the
other sector line tape and holds the 12 meter mark of the cross measuring
tape at the 20 meter mark. The sector lines are centered on the stop board
and permanent pins or stakes are placed at the ends of the sector lines.
The sector lines can be extended if longer throws than the ends of these
sector lines (18.93 m) are anticipated.
Sectors for the discus and hammer are set up in a similar manner, keeping
the ratio of cross measurement length to sector line length at 0.6. For
example, one might use sector lines of 60 m and a cross measurement of 36 m
for the discus and 70 m sector lines and a cross measurement of 42 m for the
hammer.
Note that the javelin sector is set out in a similar manner, except the
sector angle is 28.96 degrees, which is the angle between the two equal
sides of an isosceles triangle having the unequal side 0.5 times the length
of the equal sides and is mathematically expressed as 2arcsin(0.25).
Sector Illustration