80 -I V.I7.) //< <./ \// //;> [Cn. II. 



with tin* initial lino OR. hut tin- same point maybe gi\m 

 equally well by the pairs of coordinates : ("8, 

 300), and ("8, -120); and so in general. 



ff 



o 



/ .-i 



r~ 



EXERCISES 



1. Plot accurately the following points: (2, 20), (2, *Y ( -7, 5\ 



,^!), (2, 14 O. (-1, -180), (7, -45), (-7,135), (, ^). 



f i)' ('T)' (8>aD)t and ( " 6 ' 0) ' 



2. Construct the triangle whose vertices are: (2,-), ( '$, ^j 



(E \ \ 8/ \ 4 / 



1, ) ; find by measurement the lengths of the sides and the coordi- 



nates of their middle points. 



3. The base of an equilateral triangle, whose side is 5 inches, is taken 

 as the polar axis, with the vertex as pole; find the coordinates of the 

 other two vertices. 



4. Write three other pairs of coordinates for each of the points 

 (-'.): ( 170 ): (:..0); (0,60). 



5. Where is the point whose radius vector is 7? whose radius vector 

 is -7? whose vectorial angle is 25? whose vectorial anple is 0< r >? whose 

 rectorial angle is -180? 



6. Express each of the conditions of Ex. 5 by means of an equation. 

 7 What is the direction of the line through the points (a, j) and 



'?) 



24. Notation. In tin- following pages, to secure uniformity 

 and in accordance with Art. 0, a variable point will be desig- 



