Click here for my solution.
And click here for an even easier alternative. :) [...similar to Rachel's tutor's solution]
(Note: My earlier answer of 6 sq cm is wrong! It should be 9 sq cm. Apologies for any inconvenience caused. :) )
(My Learning Point: the "assigning of variables" should be done in the area where there are physical units added, and not in the area where the units are easily cancelled off. That will defeat the purpose of "assigning of variables" in the first place! )
And click here for an even easier alternative. :) [...similar to Rachel's tutor's solution]
(Note: My earlier answer of 6 sq cm is wrong! It should be 9 sq cm. Apologies for any inconvenience caused. :) )
(My Learning Point: the "assigning of variables" should be done in the area where there are physical units added, and not in the area where the units are easily cancelled off. That will defeat the purpose of "assigning of variables" in the first place! )
