26 pyeamidal system. 90. In a combination of the forms Mo, 001, the faces of the form Mo make right angles with those of the form 001 In combinations of the form Mo with the forms loo, no, the edg e e S s°p ^ ^ the ed S es K ’ ^ &ces of no truncate the^neares^f! 0 any ,/ aCe of *he form Mo makes with normals to the nearest faces of 10 o, no angles i K , |f respectively. Mo ins fnn.T , c bo , Undedb ythe alternate faces of the form and anv two « i°° S ’ °/j b ich any two opposite faces are parallel, 7 adjacent faces are perpendicular to each other. PIG. 34. faces.' ^ f ° m M (fig ' 34 ) ^s eight tan|L = IcotE, a cosf = (sin|L) a . wit 9 h 3 ;w COmbinations of the form hoi S ht^S. 001 ’ 10 °’ 110 ’ the fac ee of faces of lnr^+i. S ? lld , an " lea in which the edges f meet; the the solid amrle™ a* f edgeS L ’ and the faces of 110 truncate d S es m which the edges l, f meet. hol,00\ = 00°— i L , *o/,ioo = i L , cos (AoZjllo) = COS4o°COS^l. 94. In the form Mol (fig. 35), u = i 8 o°, t) t = 180 o_ f> wit 9 hth P n r mbination8 of the f orm 1 2 trt c rx b T’ no ’ thefaces ° f Of now! ed e es tJ; the faces faces of mo t edges v » and the which the edg™vmeet SOlid “ faces. Th ° f ° m Ul ^ 3e ) has eight I '■ ^C0S45°C0tE, COSK = (gin l L )a_ »f «■» form FIG. 35. FIG. 36. tanfi f tl wi f h ^0 forms 001, 100 „ 0 n faces of 001 truncate'the solid n 1 “ wW1 ‘«%» «"It
