trapesium pqrs dan abcd sebangun . pnjang ab=30 m dc=20 m de=15 m dan pq=18 m . jk ukuran keramik 20 cm ×10 cm byk keramik yg dibutuhkan adl

Materi : kesebangunan
Kelas : 9 SMP

Soal ini terdapat pd buku fokus UN SMP 2017

Penjelasan

PQ/AB = t / DE
18/30 = t/15
30t = 18 × 15
t = 270/30
t = 9 m

PQ/AB = SR/DC
18/30 = SR/20
30 SR = 18 × 20
SR = 360/30
SR = 12 m

L ABCD = 1/2 × (AB + DC) × DE
= 1/2 × (30 + 20) × 15 m²
= 1/2 × 50 × 15 m²
= 375 m²

L PQSR = 1/2 × (PQ + SR) × t
= 1/2 × (18 + 12) × 9 m²
= 1/2 × 30 × 9 m²
= 135 m²

L jalan = 375 m² - 135 m²
= 240 m²

banyak keramik = 240 m² / (20 × 10 cm²)
= 2.400.000 cm² / 200 cm²
= 12.000 buah