giup minh vời ạ!!!!!!! Tính diện tích:

giup minh vời ạ!!!!!!!
Tính diện tích:
giup-minh-voi-a-tinh-dien-tich

0 thoughts on “giup minh vời ạ!!!!!!! Tính diện tích:”

  1. Solution:

    $\dfrac{125}{2}$

    Step by step solution:

    Applying Pythagoras’Theorem in triangle ADB, we get:

    $\quad BD^2 = AD^2 + AB^2$

    $\Leftrightarrow BD^2 = 12^2 + 5^2$

    $\Leftrightarrow BD^2 = 169$

    Square root both side, we get:

    $\quad BD = 13\ (cm)$

    So that, the area of the quadrilateral $ABCD$ as the following:

    $\quad S_{ABCD}= S_{ABD} + S_{DBC}$

    $\Leftrightarrow S_{ABCD}=\dfrac12AD.AB + \dfrac12DB.BC$

    $\Leftrightarrow S_{ABCD}= \dfrac12\cdot 12\cdot 5 +\dfrac12\cdot 13\cdot 5$

    $\Leftrightarrow S_{ABCD}= \dfrac{60}{2} +\dfrac{65}{2}$

    $\Leftrightarrow S_{ABCD}=\dfrac{125}{2}\ (cm^2)$

    Answer: $\dfrac{125}{2}\ cm^2$

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