... mat c l i thdp B cao loom Tir dinh B v i chin C c i a r - - - thip nhin diim A b chgn ddi duiri cic g6c tuung h g bang 60' VA 30' (11 11 ) Tinh chi& cao h ciia quH ddi 49 dB cao 92 0 m, tir met ... 15,62.6 = 93 ,72 (cm) KA AH IBC Theo he th* lu(mg v6 canh g6c vubng v6i hinh chi&ucha n6 tr&ncanh huy&n,ta c : A B ~a-= 78,12 AB2 = BH BC, suy BH = BC 122 6 099 ,61 122 w 50 (cm) A C ~=-= 93 ,722 8783.44 ... tuy&n cha d~rbngtrbn ( ) c3 A vh J3 n6n OA AM vh OB 1BM, Go d6 , A = 90 ' vh = 90 ' MA IMB n t n ; n G = 90 ° Tir giic AMBO c = = = 90 ' , n&n 18 hinh chii nhgt Hinh chii nhgt nhy lai A P M c6 OA =...