Question
The length of each side of a rhombus is 10 and the measure of an angle of the rhombus is 60. Find the length of the longer diagonal of the rhombus.
Asked by: USER6966
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147 Answers
Answer (147)
Long Diagonal = side * square root (2 + 2 * cosine (smaller angle))
Long Diagonal = 10 * square root (2 + 2 * cos (60))
Long Diagonal = 10 * square root (2 + 2 * .5)
Long Diagonal = 10 * square root (2 + 1)
Long Diagonal = 10 * square root (3)
Long Diagonal = 10 * 1.7320508076
Long Diagonal = 17.320508076
Source:
1728.com/quadrhom.htm
The rhombus can be divided into two equilateral triangles. The longer diagonal is twice the length of the altitude of the triangle.
An equilateral triangle has an altitude that is (√3)/2×s, where s is the side length. Twice that value is s√3. Here, the side lenght is 10, so the longer diagonal is
... 10√3 ≈ 17.32