] nit. mu/0m //.vjr 85 



tl 

 /', dran /V/ parallel to 



uul 



.J//' in /; 



ingle 7i' 



the anglt A/ / ^0; 



beno. 



[Since -fcP-y-y, an.l /',/' 



lli.i: If-lfl = **(-' |)j . . [11] 



i i* the desired equal 



COH. If the given point be s(0, / In* jM.int in 



which the line meets the y-axis, then equation [11] Incomes 



If = mx + b. . . [ PJ ] 



m { PJ] is usually spoken of as the slope form of 

 the equation ot u^lit line. 



EXERCISES 



1 \Vhat do the ooiuUnU m and b in equation [12] memo? Draw 

 the line (or which m = 4 and 6 = 3; alao that for which m = - 1 and 

 * = 



2 What i the effect on th. line [12] of a change in 6 while m 

 remains the tame? What if m be changed and 6 left unchanged? 



3 Describe the effect on th<- 1m- [1 1] .,f changing M while r, and y, 

 remain the tame ; alao the effect resulting from a change in x, while m 

 and jr, remain the same. 



4 Write the equation of a line through the point ( 3, 7), and mak- 

 ing with the r^zis an angle of 80*; of -SO ; of (^J 8 of f 



& Write the equations of the following lines : 



(a) slope 3, y-intercept 8 ; (ft) slope , jr-intercept ~3 ; 

 (y) slope -, jrinterce) 



