A stop sign is cut out of this 2-foot square piece of metal, as shown in the figure below. The side lengths that coincide with the edges of the metal are 1 foot, as not shown in the figure below. How much metal is not used?

*Solution to yesterday’s problem:*

We are given the initial height *i*, so our equation becomes . To find the time when , let’s substitute in the variable and solve:

Moving the variable to the other side to handily avoid a negative coefficient, we get

Taking the square root of both sides,

Algebraically speaking, it could of course be positive or negative 60; but we can ignore the negative value because there would be no negative time. Finally, we arrive at the solution that the object would hit the ground *15 seconds* after dropping.

(Diagrams created with the Isosceles iOS app.)

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