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loganguyendinhhieu
2 năm trước
Cho ΔABC: góc A = 90 độ, AB = 30cm, AC = 40cm: AK⊥BC (K∈BC) a) tính độ dài BC, AK b) Chứng minh: AB2 = BK.BC c) gọi điểm D là điểm đối xứng của B qua K. Chứng minh ΔKAD đồng dạng với ΔKCA d) Qua D kẻ đường thẳng a sao cho a⊥BC và đường thẳng a cắt AB tại H. Tính diện tích tam giác BDH
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