Những câu hình hoc 10 ôn thi GHKI môn Toán Trường Lê Minh Xuân

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MA+MB+MC+MD

=MG+GA+MG+GB+MG+MC+MG+MD

=4MG+GA+GB+GC+GD

=4MG+2GE+2GF (TÍNH CHẤT HÌNH BÌNH HÀNH)

=4MG (GE+GF=0,VECTẺR ĐỐI)

GIẢI:

2AM=AB+AC TÍNH CHẤT HÌNH BÌNH HÀNH

=AB+32AK

=>AM=12AB+34AK

ĐỀ VIẾT SAI.

GIẢI:

AH=GB=-BG=-23BD=-13BA+BC=-13BA+BA+AC

=-132BA+AC=-23BA-13AC=23AB-13AC

3HB=3AG=3.23.AI=2AITÍNH CHẤT TRỌNG TÂM

2AI=AB+AC (TÍNH CHẤT hbh)

6IH=-6HI=-3.2HI=-3HB+HC  (TÍNH CHẤT hbh)

=-3HA+AB+HA+AC=-32HA+AB+AC

=-6HA-3AB-3AC=6AH-3AB-3AC

=623AB-13AC-3AB-3AC CÂU A

=4AB-2AC-3AB-3AC=AB-5AC


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