BOOK V. 11. 3-5 



of square feet. Similarly we shall always multiply 

 the feet of the length with those of the width. 



240 feet 



120 



feet 



28,800 square feet 



120 



feet 



240 feet 



But if the field is wedge-shaped (for instance, 

 suppose it to be 100 feet long and 20 feet broad on one 

 side and 10 feet on the other side) we shall add the 

 two breadths together, making a total of 30 feet. 

 Half of this sum is 15, and by multiplying the longi- 

 tude by 15 we shall obtain the result of 1500. We 

 shall say then that this is the number of square feet 

 in the wedge-shaped field which will be a semuncia 

 plus three scripula (ofg of ^ iugerum)."' 

 100 feet 



20 feet 



1500 square feet 



10 feet 



100 feet 



But if you have to measure a triangle with three 

 equal sides, you will follow this formula. Suppose 

 the field to be triangular, three hundred feet on every 

 side. Multiply this number by itself and the result 

 is 90,000 feet. Take a third part of this sum, that is 



15 



