A parallelogram has sides with lengths of #7 # and #16 #. If the parallelogram's area is #14 #, what is the length of its longest diagonal?

1 Answer
Apr 9, 2016

Longest diagonal has a length of approximately #22.96# units

Explanation:

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Using a side of length #7# as the base
#color(white)("XXX")#the height #color(blue)(h = 2)#
#color(white)("XXXXXXXXX")#since base #xx# height #= 14#

The extension of the side with length #7# to a point perpendicularly below the furthest point of the diagonal
has a length given by the Pythagorean Theorem as
#color(white)("XXX")color(red)(x=sqrt(16^2-2^2) =sqrt(252))#

The length of the base plus the extension is
#color(white)("XXX")7+color(red)(sqrt(252))~~22.87#

By the Pythagorean Theorem, the longest diagonal,
#color(white)("XXX")color(green)(d)=sqrt(22.87^2+color(blue)(2)^2)~~22.96#