The equation that models the height above or below equilibrium in inches, h, of a spring over
time in seconds, t, is h=-15 cos(2pi/5 t.
At which times will the spring be at a height of 8 in.
above equilibrium? Select all that apply.
4.2 seconds
D 1.7 seconds
0 2.9 seconds
0.8 seconds
00 3.3 seconds

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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