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Lamoanh0311
2 năm trước
Cho tam giác ABC, có AB=AC =10cm,BC =12cm. Kẻ AH vuông góc với BC tại H. a) chứng minh H là trung điểm của BC b)tính AH c)kẻ HI vuông góc với AB tại I, HK vuông góc với AC tại K, vẽ các điểm D và E sao cho D, E lần lượt là trung điểm của HD và HE . C/m AE =AH. Tam giác ADE là tam giác gì ? Vì sao d) c/m AH là đường trung trực của DE e)tìm điều kiện của tam giác ABC để A là trung điểm của DE
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