Những câu hỏi liên quan
Bui tien dung
Xem chi tiết
Cvanbinhbl huynh
Xem chi tiết
phung ngoc bi mat
Xem chi tiết
VuiLaChinh
11 tháng 3 2017 lúc 20:28

A B M C

a) M điểm giữa của BC nên CM = MB

Tam giác ABM và tam giác ACM có : đáy CM = MB, chung đường cao tương ứng với đáy.

Nên S(ABM) = S(ACM)

b) S(ABC) = S(ABM) + S(ACM) mà S(ABM) = S(ACM)

Nên  \(S\left(ABM\right)=\frac{1}{2}S\left(ABC\right)\)

Bình luận (0)
phung ngoc bi mat
13 tháng 3 2017 lúc 11:28

1/2 1000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000% luob

Bình luận (0)
phung ngoc bi mat
20 tháng 4 2017 lúc 19:54

1/2 dung 100000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000% luon minh the

Bình luận (0)
Mai 5a4
Xem chi tiết
vu pham yen ngoc
Xem chi tiết
Vũ Như Mai
21 tháng 1 2017 lúc 22:07

Sr nãy giờ quên mất câu này

A.

Ta có diện tích AMC < diện tích BMC vì AM < BM (gt)

B.

Ta có diện tích BNC < diện tích BMC vì NC < BM 

Hình bạn tự vẽ vì cũng dễ mà

Bình luận (0)
Phạm Quang Huy
Xem chi tiết
le thi thanh thuy
Xem chi tiết
Lê Anh Tú
7 tháng 1 2018 lúc 15:27

A B C M N

Mà BM=MN=NC(gt)

=> BM=MN=NC=BC/3   (*)

Từ A ta có : \(AH\perp BC\)

Từ đó ,ta thấy : Chiều cao AH của tam giác ABC cũng là chiều cao của tam giác ABM,AMN,ANC chung đáy BC/3 ( từ *)

<=> S ABM=S AMN = S ANC  => S ABC: 3

=77,4:3=25,8 cm2

Vậy ... 

Bình luận (0)
Dang Thi Huyen Trang
Xem chi tiết
LOVE TFBOYS
Xem chi tiết