tolong jwb brailny plisss

No 20.

luas 1/2 lingkaran = 1/2 x 3,14 x 10 x 10
                             =  157 dm²


luas persegi = s x s
                     = 20 x 20
                     = 400 dm²

luas persegi + luas 1/2 lingkaran = 157 dm² + 400 dm²
                                                     = 557 dm²

luas belah ketupat = 1/2 x diagonal 1 x diagonal 2
                              = 1/2 x 20 x 20
                              = 200 dm²

luas seluruhnya = luas gabungan - luas belah ketupat
                          = 557 dm² - 200 dm²
                          = 357 dm²

jawabannya c. 357 dm²