Question

[samsung]

mot cot co thang dung co bong in xuong mat dat dai 15cm(AC=15cm), cung thoi diem do, mot coc sat DE cao 2m vuong goc voi mat dat cobong in tren mat dat dai 3cm(CD=3cm) tinh chieu cao cot co (AB=?) , biet DE song song voi Ab

Answer 1

[Nguyễn Lê Phước Thịnh]

Sửa đề: DE=2cm

Xét ΔABC có DE//AB
nên \(\dfrac{DE}{AB}=\dfrac{CD}{CA}\)

=>\(\dfrac{2}{AB}=\dfrac{3}{15}=\dfrac{1}{5}\)

=>\(AB=2\cdot5=10\left(cm\right)\)