The longer base of an isosceles trapezoid measures 18 ft. The nonparallel sides measure 10 ft, and the base angles measure 80°. Find the length of a diagonal. Find the area.

Question

lukebluefive · Answer

Well, since the top and bottom of the trapezoid are parallel, the top and bottom angles on each side must sum to 180 degrees.  This means:
$$Top = 180 - 80 = 100$$
So the top angles are 100 degrees.

lukebluefive · Answer

Now, we need to find the difference between the top and the bottom lengths.  To do this, we create right triangles on each side by drawing two lines from the top points to the base.  This happens to form a rectangle in the middle, as well.
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lukebluefive · Answer

Now, adding the angles:
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