If 
such that AB = 5 cm, area (
) = 20 cm2 and area (
) = 45 cm2 , determine DE.
We have
ABC
DEF
Where AB= 5cm
Area (
) =20cm2
Area (
) =45cm2
By area of similar triangle theorem
Area (
) =AB2
Area (
) DE2
52/DE2=20/25
25/DE2=4/9
5/DE=2/3
DE=3x5/2
DE=7.5 cm
16