tolong ya terima kasih

Luas layang= 1/2 x d1 x d2
420 = 1/2 x 8+EC x 30
420 = 8+EC x 15
420/15 = 8+EC
28 = 8 + EC
28-8 = EC
20 = EC.
Jadi Diagonal 1 = 8 + 20 = 28 cm.
Dik: AD=AB dan CB=CD.
AD=AB= √8² + √15² = 17 cm
CB=CD= √15² + √20² = 25 cm
Keliling = AD + AB + CB + CD
Keliling = 17 + 17 + 25 + 25 = 84 cm. Yang B