Jawabanmu

2014-06-02T13:55:16+07:00
Ljuring ABC =  \frac{60}{360} x π x 21 x 21
                  =  \frac{1}{6} x π x 441
                  =  \frac{441}{6} π cm²
Ljuring AED =  \frac{60}{360} x π x 7 x 7
                  =  \frac{1}{6} x π x 49
                  =  \frac{49}{6} π
Larsir = Ljuring ABC - Ljuring AED
         =  \frac{441}{6} π -  \frac{49}{6} π
         =  \frac{392}{6} π cm²
Jadi, jawabannya C