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    Question

    On a rectangular wall of length 20 metres and height 21

    metres, there is a window in the shape of triangle surmounted on a square. If the base of triangle and square overlap and length of each side of the square is 6 metres and length of altitude of the triangle is 3 metres, then excluding the window, what is the surface area (in m2) of the wall?
    A 375 Correct Answer Incorrect Answer
    B 325 Correct Answer Incorrect Answer
    C 335 Correct Answer Incorrect Answer
    D 345 Correct Answer Incorrect Answer
    E None of these Correct Answer Incorrect Answer

    Solution

    Surface area of the entire wall = length × height = 20 × 21 = 420 m2 Surface area of the window = Sum of surface area of the square part + surface area of the triangular part = 62 + (1/2) × 6 × 3 = 36 + 9 = 45 m2 So, desired surface area = 420 – 45 = 375 m2

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