find the smallest angle of this pentagon x, x-15, x-50, x-30, x-40

Answer 1

Cannot be answered with the information given.
e.g. let x = 60
then you have sides of 60, 45, 10, 30, and 20
Use a ruler and a compass and a scale factor of 1/10,
that is, sides of 6, 4.5, 1, 3, and 2 inches (or cm or..)
construct such a pentagon.
(I actually cut some bamboo skewers to those lengths and formed a pentagon
I was able to "squish" the shape and change the angles.)
Try it.

There is no unique answer to the question.

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Show that a quadrilateral of sides 3, 4, 5, and 6 has the largest area when opposite angles are supplementary.