1).

Luas

Persegi:

L = s × s = 30 × 30 = 900 cm²

¼ lingkaran:

L = ¼ × π × r² = ¼ × 3,14 × 30 × 30

= 3,14 × 7,5 × 30 = 706,5 cm²

Total: 900 + 706,5 = 1.606,5 cm²

Keliling

Sisi lurus (4):

K = 4 × 30 ← 1 sisi lurus panjangnya 30 cm

= 120 cm

Sisi lengkung (¼ lingkaran):

K = ¼ × π × r × 2 = ½ × π × r

= ½ × 3,14 × 30 = 3,14 × 15 = 47,1 cm

Total: 120 + 47,1 = 167,1 cm

2).

Luas

Segitiga:

L = ½ × a × t = ½ × 8 × 6

= 4 × 6 = 24 cm²

½ lingkaran:

d = 10 cm, r = d/2 = 10/2 = 5 cm

L = ½ × π × r² = ½ × 3,14 × 5 × 5

= 3,14 × 2,5 × 5 = 39,25 cm²

Total: 24 + 39,25 = 63,25 cm²

Keliling

Sisi lurus:

K = 6 + 8 = 14 cm

Sisi lengkung (½ lingkaran):

K = ½ × π × d = ½ × 3,14 × 10

= 3,14 × 5 = 15,7 cm

Total: 14 + 15,7 = 29,7 cm

3).

Luas

Luas seluruhnya (½ lingkaran):

d = 14 + 14 + 14 = 42 cm

r = d/2 = 42/2 = 21 cm

L = ½ × π × r² = ½ × 22/7 × 21 × 21

= ½ × 22 × 3 × 21 = 11 × 3 × 21 = 693 cm²

Luas tidak diarsir (½ lingkaran):

d = 14 cm, r = d/2 = 14/2 = 7 cm

L = ½ × π × r² = ½ × 22/7 × 7 × 7

= ½ × 22 × 7 = 11 × 7 = 77 cm²

Luas diarsir: 693 - 77 = 616 cm²

Keliling

Sisi lengkung besar (½ lingkaran):

K = ½ × π × r × 2 = π × r

= 22/7 × 21 = 22 × 3 = 66 cm

Sisi lengkung kecil (½ lingkaran):

K = ½ × π × r × 2 = π × r

= 22/7 × 7 = 22 cm

Sisi lurus:

K = 14 + 14 = 28 cm

Total: 66 + 22 + 28 = 116 cm