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Let ABCD be a convex quadrilateral with AB = a, BC = b, CD = c and DA = d. Suppose a2 + b2 + c2 + d2 = ab + bc + cd + da, and the area of ABCD is 60 square units. If the length of one of the diagonals is 30 units, determine the length of the other diagonal. |
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Answer» a2+b2+c2+d2 = ab+bc+cd+da ) (a - b)2+(b - c)2+(c - d)2+(d - a)2 = 0 ) a = b = c = d. Thus ABCD is a rhombus and [ABCD] = (1/2)(d1d2) .....(1) where d1 and d2 are the lengths of the diagonals. Hence d2 = (2[ABCD])/d1 = 4units. |
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