Giai Goc l e c h cua t i a s a n g d o : D i = A(nd - 1) = ( , - 1) = 2,572° Goc l e c h cua t i a s a n g t i m : Dg = A(nt - 1) = ( , - 1) = 2,74° Goc l e c h giffa h a i t i a : A D = Dz - D i = 2,74 - , = 0,168° Vay chgn dap an D Cau 27: T a i m o t n o i t r e n m a t d a t , l a c dofn c6 c h i e u d a i C d a n g dao dong d i e u h o a v d i c h u k i 2s K h i t a n g c h i e u d a i c u a c o n iSc t h e m c m t h i c h u k i dao d o n g d i e u h o a cua n o l a 2,2s C h i e u d a i t b a n g : A 2,5 m B m C m D 1,5 m Giai B a n d a u , c h u k i dao d o n g c u a c o n l&c l a : T, =271 - = 2(s) (1) Sau k h i t a n g t h e m c m , c h u k i dao d o n g c u a c o n ISc l a : T,=2.Alil=2.2(s) (2) TCr (1) v a (2) t a c6: = 1.1- = , p = — = = n 6 .25 Vay chgn dap an B Cdu 30: H i e n tiTofng