two adjacent sides of a parallelogram are of length 5cm and 7cm and the diagonal connecting the ends of these sides is of length 9cm find the area of the parallelogram
Area of parallelogram ABCD = 2 × Area of triangle ABD.
Since, we have three sides of a triangle and not the altitude.
So, we cannot use the formula:
Area of triangle × Base × Height
We have to use the Heron's formula.
Were a, b and c are the sides of the triangle and s is the semi perimeter.
But this formula is beyond your grade level.