UPSC 2016 CDS I Math Paper

ΔABC is an isosceles triangle.Draw AD ⊥ BC.
In an isosceles triangle, the perpendicular drawn to the base from the vertex opposite to the base bisects the base.
Therefore, D is the mid-point of BC.
⇒BD=DC=

300

2

=150units
In right ΔABD,
=√6400=80 units
Therefore, area of ΔABC
=

1

2

×BC×AD=

1

2

×300×80
=12,000 square units