Draw ||gm ABCD, with AB and CD as the short sides and angle ABC obtuse. Draw diagonal BD = 14 cm and diagonal AC = 16 cm. Let E be the point of intersection of the two diagonals.
Diagonals of a ||gm bisect each other, so BE = ED = 7 and AE = EC = 8
It is also given that AB = CD = 10.
In triangle ABE, use the cos law to find angle BEA.
In triangle BCE, use the fact that angle BEC is supplementary to angle BEA to find its value. You now have enough information to find side BC, using the cos law.
A diagonals of a parallelogram measure 16cm and 14 cm respectively. The shorter side measures 10cm. find the longer side.
1 answer
1 answer