Angle trisection drawn through formula_25 to the semicircle, resulting in the intersection formula_28. The angle formula_48 generated by formula_49 and formula_50 is the angle formula_51 sought. Another means to trisect an arbitrary angle by a "small" step outside the Greek framework is via a ruler with two marks a set distance apart. The next construction is originally due to Archimedes, called a "Neusis construction", i.e., that uses tools other than an "un-marked" straightedge. The diagrams we use show this construction for an acute angle, but it indeed works for any angle up to 180 degrees. This requires three facts from geometry (at
Type 97 90 mm Infantry Mortar Light Trench Mortar, Manufactured in 1942, Osaka Army Arsenal". The Type 97 is approximately lighter than the Type 94 90-mm mortar. This weight saving was created largely by the elimination of the Type 94's recoil mechanism, which weighed . The bipod assembly of the Type 97 is lighter than that on the Type 94. There is a cover for the level on the yoke of the Type 97 which is not on the Type 94, and the sliding bracket of the Type 97 is hinged to permit its easy removal from the leg of the bipod, whereas it is integral