22 Domestic Science 



is bent in any way so as to distort either square, the 

 latter ceases to be a plane figure. 



16. In measuring small areas, the units generally 

 adopted are the square inch and the square centimetre 

 in the British and Decimal systems respectively. 

 By a square inch (or square centimetre) is meant an 

 area equal to that contained within a square the 



Fig. 7. 



length of the side of which is one inch (or one centi- 

 metre). Since 1 foot = 12 inches, and 1 decimetre = 

 10 centimetres, it may readily be shown that 1 square 

 foot, i.e. an area equal to that contained within a square 

 the length of the side of which is 1 foot, contains 

 144 square inches, and 1 square decimetre is equal to 

 100 square centimetres. Thus Fig. 7 represents a square 

 foot divided into square inches and a square decimetre 

 divided into square centimetres, both being drawn to 



