Kiểm tra 15 phút môn Hình 8

Kiểm tra 15 phút Môn Hình 8 Họ và tên:...................................... Lớp:............................................... Điểm Câu 1: Cho độ dài đoạn thẳng AB = 25 cm, CD = 170 mm khi đó, tỉ số của hai đoạn thẳng là: A. B. C. D. Câu 2: Cho tam giác ABC, đường thẳng a song song với BC, cắt AB tại M, cắt AC tại N, khi đó: A. B. C. D. Cả A, B, C Câu 3: Tìm khẳng định sai trong các khẳng định sau: A. Hai tam giác đều luôn đồng dạng với nhau B. Hai tam giác bằng nhau luôn đồng dạng với nhau C. Hai tam giác vuông luôn đồng dạng với nhau D. Hai tam giác cân có góc ở đỉnh bằng nhau luôn đồng dạng với nhau Câu 4: Cho A'B'C'ABC theo tỉ số k= (hình vẽ), khi đó tỉ số đường cao và tỉ số diện tích của hai tam giác A'B'C' và ABC là: A. B. C. D. Câu 5: Cho tam giác ABC vuông tại A, đường cao AH, có AB = 3cm, AC=4cm a) Nêu tên các cặp tam giác đồng dạng (giải thích vì sao) b) Tính BC, HB, HC? 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