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The cross section of a uniform prism is a right-angled triangle with sides 3cm, 4cm and 5cm. If its length is 10cm. Calculate the total surface area

A. 142cm

B. 132cm

C. 122cm

D. 112cm

**Comments**

Use this formula surface area of a prism = PH + 2B. Where P is the base perimeter, H = height, B = base area

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since the base area is a right angled triangle, There fore: the area of a right angle triangle, B = 1/2(Base * height)

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The base perimeter is the sum of all the bases, i.e: 3 + 5 + 5

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surface area of a prism = PH + 2B

P = perimeter of bases = sum of all bases = 3 + 4 + 5 = 12cm

H = height = 10cm

P*H = 12 * 10 = 120cm^{2}

B = area of the base = 1/2(b*h) = 1/2(3*4) = 6cm^{2}

surface area of prism = 120 + 2(6)

= 132cm^{2}

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