a)write down the equation of the family of straight lines with slopes equal to 2
b)find the equations of the straight lines in the family in(a) which are square root 5 units from the point(1,1)
amaths analytical geometry
2012-03-29 9:41 am
回答 (1)
2012-03-29 10:05 am
✔ 最佳答案
a)y = 2x + C i.e.
2x - y + C = 0 where C is a real constant.
b)| ( 2(1) - (1) + C ) / √(2² + 1²) | = √5| ( 1 + C ) / √5) | = √5( 1 + C ) / √5 = ±√51 + C = ±5C = ±5 - 1 = 4 or - 6The required equations are 2x - y + 4 = 0 and 2x - y - 6 = 0 .
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