Question

ABCD is a quadrilateral. Work out the length of CD. Give your answer to 3 significant figures

Answer 1

Check the picture below.

`sin(35^o)=\cfrac{\stackrel{opposite}{12}}{\underset{hypotenuse}{BD}}\implies BD=\cfrac{12}{sin(35^o)} \\\\[-0.35em] ~\dotfill\\\\ \textit{Law of sines} \\\\ \cfrac{sin(\measuredangle A)}{a}=\cfrac{sin(\measuredangle B)}{b}=\cfrac{sin(\measuredangle C)}{c} \\\\[-0.35em] ~\dotfill`

`\cfrac{sin(52^o)}{BD}=\cfrac{sin(102^o)}{CD}\implies CD=\cfrac{BD\cdot sin(102^o)}{sin(52^o)} \\\\\\ CD=\cfrac{(12)/(sin(35^o))\cdot sin(102^o)}{sin(52^o)}\implies CD=\cfrac{12\cdot sin(102^o)}{sin(35^o)\cdot sin(52^o)}\implies CD\approx 26.0`