moi nguoi giup minh voi

Đáp án:

$CD\approx 22,7722\ m$

Giải thích các bước giải:

Ta có:

$C_1D = A_1C_1.\tan\widehat{DA_1C_1}$

$C_1D = B_1C_1.\tan\widehat{DB_1C_1}$

Do đó:

$\quad A_1C_1.\tan\widehat{DA_1C_1}=B_1C_1.\tan\widehat{DB_1C_1}$

$\Leftrightarrow A_1C_1.\tan49^\circ = (A_1C_1 + 12).\tan35^\circ$

$\Leftrightarrow A_1C_1 =\dfrac{12.\tan35^\circ}{\tan49^\circ - \tan35^\circ}$

Ta được:

$\quad CD = CC_1 + C_1D = 1,3 + \dfrac{12.\tan35^\circ}{\tan49^\circ - \tan35^\circ}\cdot \tan49^\circ$

$\Leftrightarrow CD\approx 22,7722\ m$