40 



PEACTICAL MEASUREMENTS 



TRIANGULAR DIAGRAM 



45. A triangular field is one bounded by three straight lines. 



The altitude of a triangle 

 is the perpendicular distance 

 between the base of the tri- 

 angle and the highest point 

 opposite it. 



Lines are perpendicular (J_) 

 to each other when they meet 

 forming a square corner. 



If two sides of a triangle are 

 perpendicular to each other, 

 the triangle is called a right 

 triangle. 



EXERCISE 



1. Cut a 4-inch square into 2 equal right triangles. How 

 many square inches are there in each triangle ? At a point 

 halfway between the base and 



the apex of one of the trian- 

 gles, cut on a line parallel with 

 the base, and so place the two 

 parts as to form a rectangle. 

 Now make your own tule for 

 measuring a triangle. 



2. How many acres are there 

 in a triangular field the longest 

 side of which is 30 rd., and 

 the altitude of which from the 

 opposite corner to this side is 

 35 rd.? 



3. Stake off a small trian- 

 gular field, measure the longest side and the altitude from 

 the corner opposite this side, and determine the number of 

 acres. 



DIAGRAM ILLUSTRATING 



RULE FOR FINDING AREA 



OF A TRIANGLE 



