A submarine began the day at sea level. It descended 1,200 feet in one hour, and then the submarine continued to descend at a constant rate for the next 3 hours. I f the submarine was-5,465 feet below sea level after the four hours, what was the constant rate of descent during the three-hour period of time measured in feet per hour?

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step-by-step explanation:

stethere all not eveanp-by-step explanation:

we have three similar triangles, because each has a right angle and shares an angle.   let's write the angles in order: opposite to short leg, long leg, hypotenuse.

cab similar to bad similar to cbd

or as ratios,

ca: ab: cb = ba: ad: bd = cb: bd: cd

we also know

ac = ad + cd

(ad+cd): ab: cb = ba: ad: bd = cb: bd: cd

(ad+cd)/cb=cb/cd

we have cb=6, ad=5 and seek x=cd.

we reject the negative root and conclude x=4

answer: 4