4. Area = 49.2075 m²
5. Area = 63.25 m²

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Penjelasan/Explanation

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Number 4

The area of that figure equals to the area of the square minus the area of the semicircle.

• The length of each side: s = 9 m
• Radius of semicircle: r = ½s

A = s² –  ½πr²
⇔ A = s² – ½π(½s)²
⇔ A = s² – ½(¼πs²)
⇔ A = s² – (1/8)πs²
⇔ A = s²[1 – (1/8)π]
⇔ A = 9²[1 – (1/8)×3.14]
⇔ A = 81(1 – 0.3925)
⇔ A = 81(0.6075)
⇔ A = 49.2075 m²

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Number 5

The area of that figure equals to the sum of the area of the right-angled triangle and the area of the semicircle.

• Base of triangle: b = 8 m
• Height of triangle: h = 6 m
• Radius of semicircle: r = (½×10) m = 5 m

A = ½bh + ½πr²
⇔ A = ½(bh + πr²)
⇔ A = ½(8×6 + 3.14×5²)
⇔ A = ½(48 + 3.14×25)
⇔ A = ½(48 + 78.5)
⇔ A = ½(126.5)
⇔ A = 63.25 m²

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KESIMPULAN/CONLUSION

4. Area = 49.2075 m²
5. Area = 63.25 m²

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