Refer to the image attached.
Given: Altitude AC = 9 cm, Diagonal AD = 15 cm, side AB = 82 cm.
To find: Area of parallelogram
Solution:
Since, area of parallelogram = base
height
=

We have to determine the base BD.
Consider the triangle ABC,
by Pythagoras theorem,



BC = 81.5 cm
Now, Consider the triangle ACD,
by Pythagoras theorem,



CD = 12 cm
Now, base BD = BC + CD
= 81.5+12
= 93.5 cm
Area of parallelogram = BD

= 93.5 x 9
= 841.5 square centimeters.
Therefore, the area of parallelogram is 841.5 square centimeters.