Question

Berdasarkan gambar, tentukan !
a. Luas permukaan bandul
​

Answer 1

Verified answer

LP = (luas balok - luas alas balok) + (luas sisi tegak limas)

LP = (2(p×l + p×t + l×t) - p×l) + (4(10×t∆×½))

LP = (2(10×10 + 10×20 + 10×20) - 10×10) + (4(5t∆)

LP = (2(100+200+200)-100) + (20t∆)

LP = (2(500)-100) + 20t∆

LP = 1000-100 + 20t∆

LP = 900 + 20t∆

t∆ = √(12² + 5²)

t∆ = √(144 + 25)

t∆ = √169

t∆ = 13

LP = 900 + 20(13)

LP = 900 + 260

LP = 1160 cm²

Answer 2

Penyelesaian:

S = 10 cm

t1 = 20 cm

t2 = 12 cm

Tinggi sisi tegak limas (t3):

• t3 = [tex]\sqrt{(s ÷ 2)² + t2²}[/tex]
• t3 = [tex]\sqrt{(10÷2)² + 12²}[/tex]
• t3 = [tex]\sqrt{5² + 144}[/tex]
• t3 = [tex]\sqrt{25 + 144}[/tex]
• t3 = [tex]\sqrt{169}[/tex]
• t3 = 13 cm

Maka luas permukaan bangun tsb:

• = (4 × s × t1) + (s²) + (4 × [tex] \frac{s \:× \:t3}{2} [/tex])
• = (4 × 10 × 20) + (10²) + (2 × 10 × 13)
• = 800 + 100 + 260
• = 800 + 100 + 260
• = 1.160 cm²

Jawaban: 1.160 cm²