Homework Help: geometry

Posted by Anonymous on Tuesday, November 15, 2011 at 10:07pm.

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

geometry - MathMate, Tuesday, November 15, 2011 at 10:14pm
So we have a trapezoid ABCD, in which
AB=unknown
BC=10,
CD=14
DA=10
and
AC=16.

Sketch the triangle ACD for which the lengths of all three sides are known.
Using the cosine rule, calculate the cosine of A using
cosA=(AC²+AD²-CD²)/(2*AC*AD)
and hence calculate ∠A.

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