, , . . .14 ( ), . 90 80. ( "") . , ( ), , . ( ), . 10 . 70 . : 70-10 = 60 . , 60 .
.
1- . (.. ) , . (.15).
2- . . .16 225 , , , 175 . (h .17). .17, () , . .. = h cos α. h = 225-175=50 , = 50 cos 12. =500,978=48,9 . 13 , .. , .
3- . , ( ), . , ( .18), . , , , , , , . , ( 300 ). cos .