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AP Calculus AB· difficulty 4/5

L=12 h=6 x s

A 6-ft person walks from a 12-ft lamppost. By similar triangles, the shadow length ss is:

  • A

    s=xs = x

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  • B

    s=2xs = 2x

  • C

    s=6s = 6

  • D

    s=x/2s = x/2

Explanation

From similar triangles: 6s=12x+s\frac{6}{s} = \frac{12}{x+s}, so 6(x+s)=12s6(x+s) = 12s, giving s=xs = x.

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