142cm2
132cm2
122cm2
112cm2
Correct answer is B
A prism has 3 rectangular faces and 2 triangular faces and 2 rectangular faces = 10(3 + 4 + 5) = 120
Area of triangular faces = √s(s−a)(s−b)(s−c)
where s = a+b+c2
= 3+4+52
= 122
= 6
Area of △ = √6(6−30(6−4)(6−5)
= √6×3×2×1 = 6
Area of triangle faces = 2 x 6 = 12cm2
Total surface area = Area of rectangular face + Area of △ = 120 + 12
= 132cm2
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