Question

Find area of parrellogram ABCD whose adjacent sides are 60 cm, 40 cm and one diagonal is 80 cm find area? ​

Answer 1

Answer:

Let ABCD is a parallelogram in which AB= DC= 100 cm. and BC =AD= 60 cm.,

diagonal DB= 80 cm.

In triangle DAB , DA^2+DB^2= (60)^2+(80)^2= 3600+6400 = 10000……….(1)

and (AB)^2= (100)^2= 10000………………….(2). From eqn. (1) and (2)

DA^2+DB^2=AB^2. , therefore. Angle ADB= 90°.

Area of parallelogram ABCD = 2×Area of right angled triangle ADB.

= 2×1/2.(DA×DB)

= 60 cm× 80 cm

= 4800 cm^2.