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Title: A Guide to Making Your School Greener

Introduction: Welcome to our guide on how to make your school greener! By implementing sustainable practices, you can contribute to a cleaner environment and create a positive impact on the planet. In this guide, we will provide you with practical steps to help you and your school become more eco-friendly.

1. Reduce Paper Usage:
Encourage digital communication: Promote the use of emails, online platforms, and shared documents instead of relying on paper-based communication.
Opt for electronic assignments: Encourage teachers to accept electronic submissions for assignments, reducing the need for printed papers.
Utilize both sides of the paper: Encourage students and staff to print on both sides of the paper whenever possible.
2. Implement Recycling Programs:
Set up recycling stations: Place recycling bins strategically throughout the school to make it convenient for everyone to recycle paper, plastic, glass, and other recyclable materials.
Educate on proper recycling: Provide clear instructions on what can and cannot be recycled, ensuring that everyone understands the recycling process.
3. Conserve Energy:
Turn off lights and electronics: Remind students and staff to switch off lights, computers, and other electronic devices when not in use.
Utilize natural lighting: Make the most of natural light by opening curtains and blinds, reducing the need for artificial lighting during the day.
Upgrade to energy-efficient appliances: Encourage the school administration to invest in energy-efficient appliances and LED lighting, reducing energy consumption.
4. Promote Water Conservation:
Fix leaks and drips: Address any leaks or drips in faucets, toilets, or other water fixtures promptly to prevent wastage.
Encourage shorter showers: Raise awareness about the importance of shorter showers to conserve water and encourage students to be mindful of their water usage.
Collect rainwater: Install rain barrels to collect rainwater for watering school gardens or other non-potable uses.
5. Develop Green Spaces:
Start a school garden: Set up a garden where students can learn about sustainable gardening practices and grow their food.
Plant native trees and plants: Native plants require less water and maintenance, while also providing habitat for local wildlife.
Create green roofs: Implement green roofs or living walls to improve insulation and reduce energy consumption while enhancing the aesthetic appeal of the school.
Conclusion: By following these steps, you can make your school a greener and more sustainable place. Remember, small changes can have a significant impact when everyone in the school community works together towards a greener future. Start implementing these practices today and lead the way in creating a more environmentally conscious school environment.

Gọi I là tâm nội tiếp \(\Delta\)ABC, khi đó 3 điểm C,I,K  thẳng hàng. Gọi đường tròn ngoại tiếp \(\Delta\)AIE cắt tia CI tại điểm thứ hai F.

Xét \(\Delta\)CKA và \(\Delta\)CIB có: ^ACK = ^BCI (=^ACB/2); ^CAK = ^CBI (=^ABC/2) => \(\Delta\)CKA ~ \(\Delta\)CIB (g.g)

Suy ra: \(\frac{CK}{CI}=\frac{CA}{CB}\). Mà \(\frac{CA}{CB}=\frac{CD}{CA}\)(\(\Delta\)CAD ~ \(\Delta\)CBA) nên \(\frac{CK}{CI}=\frac{CD}{CA}\Rightarrow\frac{CK}{CD}=\frac{CI}{CA}\)

Lại có: CEA và CIF là 2 cát tuyến của (AIE) nên \(\frac{CI}{CA}=\frac{CE}{CF}\). Từ đó: \(\frac{CK}{CD}=\frac{CE}{CF}\)

Suy ra: \(\Delta\)CEK ~ \(\Delta\)CFD (c.g.c) => ^CEK = ^CFD. Nếu ta gọi 2 tia FD và EK cắt nhau ở L' thì ^CEL' = ^CFL'

=> Tứ giác CL'FE nội tiếp => ^ECF = ^EL'F => ^KCD = ^KL'D => Tứ giác CKDL' nội tiếp 

Áp dụng phương tích đường tròn có: FK.FC=FD.FL'   (1)

Cũng từ \(\Delta\)CKA ~ \(\Delta\)CIB (cmt) => ^BIF = ^AKI hay ^AKF = ^EIC => ^AKF = ^CAF

=> \(\Delta\)AFK ~ \(\Delta\)CFA (g.g)  => FA² = FK.FC        (2)

Từ (1) và (2) => FA² = FD.FL' => \(\Delta\)FDA ~ \(\Delta\)FAL' (c.g.c)

=> ^FL'A = ^FAD = ^DAC - ^FAC = ^ABC - ^FKA = ^ABC - (^KAC + ^ACK) = ^ABC/2 - ^ACB/2

Do đó: ^AL'E = ^FL'A + ^FL'E = ^ABC/2 - ^ACB/2 + ^ACB/2 = ^ABC/2 = ^ABE => Tứ giác ABL'E nội tiếp

Hay tia EK cắt đường tròn ngoại tiếp tam giác ABE tại L' => L' trùng L

Từ đó dễ có: ^BLC = ^ABC/2 + ^ACB + ^ABC/2 + ^BAC/2 = ^ABC + ^ACB + ^BAC/2 = 180⁰ - ^BAC/2

Vậy thì tâm của đường tròn (BLC) nằm tại điểm chính giữa cung BC chứa A của (O) (đpcm).

a: Kẻ BD vuông góc AC,CE vuông góc AB

góc BEC=góc BDC=90 độ

=>BEDC nội tiếp

=>góc AED=góc ACB

=>ΔAED đồng dạng vơi ΔACB

Tâm M của đường tròn ngoại tiếp tứ giác BDCE là trung điểm của BC

Gọi H là giao của BD và CE

=>AH vuông góc BC tại N

Gọi giao của OM với (O) là A'

ΔOBC cân tại O

=>OM vuông góc BC

AN<=A'M ko đổi

=>\(S_{ABC}=\dfrac{1}{2}\cdot AN\cdot BC< =\dfrac{1}{2}\cdot A'M\cdot BC_{kođổi}\)

Dấu = xảy ra khi A trùng A'

=>A là điểm chính giữa của cung BC

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