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imc

geometry intermediate

Problem

Rhombus is similar to rhombus . The area of rhombus is and . What is the area of rhombus ?
problem
(A)
(B)
(C)
(D)
Solution
Using the property that opposite angles are equal in a rhombus, and . It is easy to see that rhombus is made up of equilateral triangles and . Let the lengths of the sides of rhombus be . The longer diagonal of rhombus is . Since is a side of an equilateral triangle with a side length of , . The longer diagonal of rhombus is . Since is twice the length of an altitude of of an equilateral triangle with a side length of , . The ratio of the longer diagonal of rhombus to rhombus is . Therefore, the ratio of the area of rhombus to rhombus is . Let be the area of rhombus . Then , so .
Final answer
C