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![](https://rs.olm.vn/images/avt/0.png?1311)
Nửa chu vi hình chữ nhật là
32 : 2 = 16 m
Chiều dài hcn là
16 : 5 × 3 = 9,6 m
Chiều rộng hcn là
16 - 9,6 = 6,4 m
DT 1 viên gạch là
0,8 × 0,8 = 0,64 m^2
Số gạch cần lát là
61,44 : 0,64 = 96 viên
![](https://rs.olm.vn/images/avt/0.png?1311)
Diện tích 1 viên gạch hình vuông: \(40.40=1600\left(cm^2\right)\)
Diện tích khu vườn: \(1600.400=640000\left(cm^2\right)=64\left(m^2\right)\)
Độ dài mỗi cạnh: \(\sqrt{64}=8\left(m\right)\)
![](https://rs.olm.vn/images/avt/0.png?1311)
Diện tích sân hình vuông là:
3,5 x 3,5 = 12,25 ( m2 )
Diện tích viên gạch là:
25 x 100 = 2500 ( cm2 ) = 25 m2
Không thể lát gạch có kích thước 25 cm x 100 cm mà ko cắt vì kích thước gạch lớn hơn diện tích sân
Diện tích một viên gạch hình chữ nhật là: \(25\cdot100=2500\left(cm^2\right)=0,25m^2\)
Diện tích cái sân là: \(3,5\cdot3,5=12,25\left(m^2\right)\)
Vậy số viên gạch cần để lát cái sân đó là: \(12,25:0,25=49\)(viên gạch)
Vì 12,25 chia hết cho 0,25 nên không cần cắt gạch mà vẫn lát được hết cái sân
![](https://rs.olm.vn/images/avt/0.png?1311)
Lời giải:
Nửa chu vi nền nhà: $32:2=16$ (m)
Chiều rộng nền nhà: $16:(2+3)\times 2=6,4$ (m)
Chiều dài nền nhà; $16-6,4=9,6$ (m)
Diện tích nền nhà: $6,4\times 9,6=61,44$ (m2)
Độ dài cạnh 1 viên gạch: $0,8:4=0,2$ (m)
Diện tích 1 viên gạch: $0,2\times 0,2=0,04$ (m2)
Số gạch cần dùng: $61,44:0,04=1536$ (viên)
![](https://rs.olm.vn/images/avt/0.png?1311)
chiều dài bằng \(\frac{2}{3}\)chiều rộng?????
![](https://rs.olm.vn/images/avt/0.png?1311)
Gọi chiều dài viên gạch là x, chiều rộng viên gạch là y (x,y>0)
Vì viên gạch có chu vi là 80 cm nên ta có phương trình: \(\left(x+y\right).2=80\Leftrightarrow x+y=40\)(1)
Vì nếu giảm chiều dài viên gạch đi 5cm và tăng chiều rộng lên 5cm thì viên gạch có hình vuông nên ta có phương trình:
\(x-5=y+5\) \(\Leftrightarrow x-y=10\) (2)
Từ (1) và (2) ta có hệ phương trình \(\hept{\begin{cases}x+y=40\\x-y=10\end{cases}}\Leftrightarrow\hept{\begin{cases}2x=50\\x+y=40\end{cases}}\Leftrightarrow\hept{\begin{cases}x=25\\y=15\end{cases}}\)
Vậy diện tích 1 viên gạch là: 25 . 25 = 375 (cm2)
Diện tích nền lớp là: 375 . 1200 = 450000 (cm2) = 45 (m2)
Mình sửa chỗ diện tích 1 viên gạch là:
25 . 15 = 375 (cm2)
nhé. Mình viết nhầm 25 . 25
khi ghép 4 miếng gạch với nhau có hình v![](data:image/png;base64,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)
từ hình vẽ=> R=3dm=>S hình tròn =\(\pi\).R^2=3^2.\(\pi\)=9.\(\pi\)