(1) Use the formula for the area of the partallelogram
area = ,
where "a" and "b" are any two adjacent sides of the parallelogram and is the angle concluded between them.
From this formula, = = 0.5.
(2) Hence, the acute angle of the parallelogram is 30°, and the obtuse angle is 150°.
The cosine of the obtuse angle is cos(150°) = - then.
(3) Now apply the cosine rule
the length of the longer diagonal = = = 70.55 feet. ANSWER