Jawaban:

4) C. 96 cm²

5) A. 30 cm

6) D. 48 cm²

7) B. 14 cm

8) D. Segitiga lancip

9) A. 125°

10) C. 36°

Penjelasan dengan langkah-langkah:

4. L.ABC = (½ × (16 + 5) × 12) - (½ × 5 × 12)

L.ABC = 126 - 30

L.ABC = 96 cm² (C)

5. AC = √(BC² - AB²)

AC = √(13² - 5²)

AC = √(169 - 25)

AC = √144

AC = 12 cm

k = AB + AC + BC

k = 5 + 12 + 13

k = 30 cm (A)

6. k = a + 2x

32 = 12 + 2x

2x = 32 - 12

2x = 20

x = 10 cm

t = √(10² - 6²)

t = √(100 - 36)

t = √64

t = 8 cm

L = ½ × a × t

L = ½ × 12 × 8

L = 48 cm² (D)

7. L = ½ × a × t

84 = ½ × 12 × t

84 = 6t

t = 84 ÷ 6

t = 14 cm (B)

8. ∠A = 75°

∠B = 180° - 155°

∠B = 25°

∠C = 180° - (75° + 25°)

∠C = 180° - 100°

∠C = 80°

karena semua sudutnya kurang dari 90°, maka segitiga ABC adalah segitiga lancip (D)

9. ∠CAD = 180° - (90° + 55°)

∠CAD = 180° - 145°

∠CAD = 35°

∠CAD = ∠BCA = 35°

∠BCD = 90° + 35°

∠BCD = 125° (A)

10. 5x + 3x + 2x = 180°

10x = 180°

x = 180° ÷ 10

x = 18°

∠A = 2x

∠A = 2(18)

∠A = 36° (C)