no 21 tolong jawab ^^

21/3 = 7m
29 - (2x7)
= 29 - 14
= 15m

panjang busur 4 buah 1/4 lingkaran
= 4 x 1/4 x 2 phi r
= 2 phi r
= 2 x 22/7 x 7
= 44/7 x 7
= 44

keliling pagar
= 44 + (7 x 2) + (15 x 2)
= 44 + 14 + 30
= 58 + 30
= 88 m