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Lines on XY plane

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Lines on XY plane

by PankajRai » Thu Jun 16, 2011 5:44 am
I chose E? What are your options?

Line l is defined by the equation y - 5x = 4 and line w is defined by the equation 10y + 2x + 20 = 0. If line k does not intersect line l, what is the degree measure of the angle formed by line k and line w? (Assume that all lines lie in one coordinate plane.)
0

30

60

90

It cannot be determined from the information given.
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by Anurag@Gurome » Thu Jun 16, 2011 6:04 am
PankajRai wrote:Line l is defined by the equation y - 5x = 4 and line w is defined by the equation 10y + 2x + 20 = 0. If line k does not intersect line l, what is the degree measure of the angle formed by line k and line w? (Assume that all lines lie in one coordinate plane.)
The red part is confusing...

Slope of line l = 5
Slope of line k = -2/10 = -1/5

Therefore, (slope of l)*(slope of k) = -1
Hence, the lines are perpendicular to each other, i.e. the degree measure of the angle formed by them is 90.

But as they are perpendicular to each other, they are bound to intersect each other.
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by guillermocaracas » Thu Jun 16, 2011 11:46 am
Maybe this could help you.
If k does not intersect line l, then k is parallel to l, therefore slopes are equal.
correct choice should be E. it cannot be solved with the information given.
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by phoenix111 » Thu Jun 16, 2011 1:14 pm
PankajRai wrote:I chose E? What are your options?

Line l is defined by the equation y - 5x = 4 and line w is defined by the equation 10y + 2x + 20 = 0. If line k does not intersect line l, what is the degree measure of the angle formed by line k and line w? (Assume that all lines lie in one coordinate plane.)
0

30

60

90

It cannot be determined from the information given.
Since k doesnt intersect L , so they are parellal.
Therefore Eq of K => y = 5x + c ( Slope : 5)(let this be M1)

Slope of Line : W => -1/5 (let this be M2)

Since M1*M2 = -1 therefore line are perpendicular.

Answer : 90 (option D)
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by amit2k9 » Thu Jun 16, 2011 7:51 pm
line l is y=5x+4
line w is y= (-1/5)x - 10

thus l is perpendicular to w
since k does not intersect l means k || l

thus k is perpendicular to w

90 it is.
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