UPSC CDS 1 2018 Math Paper

Remember: D and E are midpoints of AB and AC. Therefore, in the equilateral triangle ABC, the area of ΔADE = area of ΔDEF = area of ΔDBF = area of ΔEFC
Area of DEBC = 3 × area of ΔADE
3×

√3

4

(

l

2

)2=

3√3l2

16