Jawaban:

A. Panjang = 10 cm

Lebar = 9 cm

Keliling = 38 cm

Luas = 90 cm²

B. Panjang = 12 cm

Lebar = 16 cm

Keliling = 56 cm

Luas = 192 cm²

C. Panjang = 8 dm

Lebar = 15 dm

Keliling = 46 dm

Luas = 120 dm²

Penjelasan dengan langkah-langkah:

Rumus Persegi Panjang:

Luas = panjang X lebar atau p X l

Keliling = 2 X (p + l)

Panjang = Keliling - (lebar X 2) / 2

Lebar = keliling - (panjang X 2) / 2

A. Keliling = 2 X (p + l)

= 2 X (10 + 9)

= 2 X 19

= 38 cm

Luas = p X l

= 10 X 9

= 90 cm²

B. Lebar = keliling - (panjang X 2) / 2

= 56 - (12 X 2) / 2

= 56 - 24 / 2

= 32 / 2

= 16 cm

Luas = p X l

= 12 X 16

= 192 cm²

C. Panjang = keliling - (lebar X 2) / 2

= 46 - (15 X 2) / 2

= 46 - 30 / 2

= 16 / 2

= 8 dm

Luas = p X l

= 8 X 15

= 120 dm²