The time, in seconds, it takes for one complete swing of a pendulum is represented by the equation below, where is the length of the pendulum in meters, and is the acceleration due to gravity (9.81 m/s2). What is the approximate length of the pendulum if it takes the pendulum 4.4 seconds to complete one full swing? (Use = 3.14)

step-by-step explanation:

geometry: triangles

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call the larger triangle abc

then the smaller triangle cde is similar to abc (all angles are equal, aaa).  

ab is the side that is 36, and we wish to find de, the side corresponding to ab

area_cde = area_abc - area_cde --> area_abc / area_cde = 2

let x=length of de

ratio of areas = (ratio of sides)^2

+2+=+%2836%2fx%29%5e2+

+2+=+1296%2fx%5e2+

++x%5e2+=+1296%2f2+=+648+

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