In the rectangle ABCD, O is any point inside the rectangle. If area(△AOD) = 30 cm2 and area(△BOC) = 60 cm2, Find the area of the rectangle ABCD. [2 MARKS]
Concept : 1 Mark
Calculation : 1 Mark
Draw a line through O parallel to AD as shown .
Parallelogram APQD and triangle AOD are on same base AD and between same parallels.
So,ar(△AOD) = 12 ar(APQD)
ar(APQD) = 60 cm2
Parallelogram PBCQ and triangle BOC are on same base BC and between same parallels.
So, ar(△BOC)= 12 ar(PBCQ)
ar(PBCQ) = 120 cm2
ar(ABCD) = ar(APQD) + ar(PBCQ) = 180 cm2