Question

diketahui layang layang ABCD dengan panjan AB = 15 cm, dan diagonal BD = 24 cm. Jika keliling layang layang tersebut 70 cm, tentukan :

a. Panjang BC

b. Panjang diagonal AC

c. Luas layang layang ABCD

Answer 1

Keliling = 2(AB + BC) [karna sisi yg bersblahan sama besar)
70 = 2(15 + BC)
70 = 30 + 2BC
40 = 2BC
BC = 20

pakai phytagoras:
AB² = AO² + BO²
15² = AO² + (24/2)²
225 = AO² + 144 >>> 12²
AO² = 225 - 144
AO = √81
AO = 9

BC² = BO² + CO²
20² = 12² + CO²
400 = 144 + CO²
CO² = 400 - 144
CO = √256
CO = 16

AC = AO + CO
= 9 + 16 = 25

luas = 1/2 . 24 . 25
= 12 . 25
= 300cm²

insya allah seperti diatas