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
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