UPSC CDS 2 2021 Math Paper

Given, the length of minute hand of the clock =21cm
Time for calculating the area is 10:10 am to 10:30 am.We know, the area of rhombus
=‌

1

2

(d1×d2)
Where, d1 and d2 are the lengths of the diagonals.
Therefore, 336=‌

1

2

×(48)
× (length of other diagonal) The length of other diagonal
=‌

336

24

=14cm
We know that, diagonals of rhombus bisect each other at right angle.
∵AO=‌

1

2

×14=7cm and
BO=‌

1

2

×48=24cm
∴ln△ABO ,
AB2=OA2+OB2
AB2=72+242
AB=√49+576=25cm .
Length of side of rhombus =25cm
Perimeter of rhombus =4×25cm
=100cm .