UPSC CDS 2 2019 Math Paper

If all the sides of a parallelogram are equal, then it is a rhombus. We know that the diagonals of the rhombus bisect each other at right-angle.
Let the diagonals are d1 and d2, then given that
‌

d1

d2

=‌

1

2

and d1+d2=12
From above two, d1=4,d2=8
Now, area of parallelogram,
A=‌

1

2

d1d2=‌

1

2

×4×8=16cm2