UNITS OF LENGTH, AREA AND VOLUME 



25 



144 square inches 

 9 square feet 



British Units of Area. 



square foot. 



y square feet = 1 square yard. 



30 square yards -= 1 square rod, pole, or perch, 



40 square poles = 1 rood. 



4 roods = 1 acre. 



640 acres = 1 square mile. 



Units of Area in the Metric 

 100 square millimetres = 1 

 10,000 square millimetres "I _ 



100 square centimetres / 

 1,000,000 square millimetres -\ _ 

 10,000 square centimetres I _ 

 100 square decimetres J 

 10 centiares 



10 declares = 1 are = 

 10 ares 

 10 dekares = 1 hectare = 



= 1 



1 



1 



1 

 1 

 1 

 1 



System. 



square centimetre, 



square decimetre, 



square metre, 

 centiare. 



deciare. 



square dekametre. 



dekare. 



square hectometre. 



Exercises in Measurement of Areas. EXPT. 30. Draw 



several right-angled triangles (as in Fig. 14) and carefully 

 measure the lengths of the sides of each of them. 



B A B A 



FIG. 14. Right- Angled Triangles. 



Square each of these numbers and set down the results in 

 parallel columns, as here shown : 



This is not only an exercise in measurement, but the results 

 will show that the square of the longest side of a right-angled 



