898 



16. Yea ; Un- y, Un- V t"*' 1 H- 



17. un-i(i), tan-i (,',), tan->(-|). 



18. Parallel if 6 = ; perpendicular if W = a* -f 1. 



19. Dteunce between lines Is 20. ^-. 81. - 26 



VlO 2V34 \ S2U 



29. They make numerically equal but opposite angles with the z-axis. 



23. Un-(-H); 7y = 9ac-l, 7x-|-9y^ 



24. 46; (-6, 3); 2z = 



Pages 107. 108 Art. 64. 



11. Altitudes are: --, -, and \^; the area is 1. 

 V34 V6 



_ y=12| and 7z+7y=S6. 



Page 110. Art. 65. 



2 Other bisector is 21 x-77y+61=0. 



_8816V2 

 142 



Page 114. Art. 67. 



1. 3y + * + 6 = 0, 2y-* + 6 = 0; (|, - V); 46. 



2. z-3y + l=0, a: + y + l=0; (-1, 0); tan~ 2. 



3 r -y(seca + tano)= 0, z - y(seca - tana) = 0; (0, 0); a. 

 4. z-f3y + 6 = 0, z-f3y 1=0; line are parallel. 



6. k = V or W the lines corresponding to* = are 

 2z + 3y + 4 = t and the angle between them is tan- C^), their point of 

 intersection is (1, -2). 



7 For k - 28 this equation represents a pair of imaginary lines. 



I. k = 4 ; the two lines coincide, the equation in (2 z - 3 y - I) 2 = 0. 



0. Or-r,y + 14 = and 6z + 6y = 60. 



10. K.-alif B*-w4C>0; imaginary if ^-^C<0; coincident if B*= A' ; 

 perpendicular if A + C = 0. 



