posted by Anonymous .
the longer base of an isosceles trapezoid is 14 feet. the nonparallel sides are each 10 feet long and the length of diagonal is 16 feet. find the measure of a base angle
So we have a trapezoid ABCD, in which
Sketch the triangle ACD for which the lengths of all three sides are known.
Using the cosine rule, calculate the cosine of A using
and hence calculate ∠A.