Math, asked by surajkv9973, 10 months ago


if the angle between the lines kx + y + 9 = 0, y - 3x = 4 is 45° the value of k is

1)-1/2
2) 1/3
3) 1/2
4)-1/3
with solutions​

Answers

Answered by amitnrw
6

value of k  =   -1/2 if the angle between the lines kx + y + 9 = 0, y - 3x = 4 is 45°

Step-by-step explanation:

kx + y + 9 = 0

=> y = -kx - 9

slope = - k

y - 3x = 4

=> y = 3x + 4

=> slope = 3

Angle between two lines = 45°

Tan 45 =  | (-k - 3)/(1 + (-k)(3)|

=> 1 = = |  (-(3 + k)/(1 - 3k) |

=> 1 = |  (k + 3)/(3k - 1) |

(k + 3)/(3k - 1) = 1

=> k + 3 = 3k - 1

=> 2k = 4

=> k =2

(k + 3)/(3k - 1) = -1

=> k + 3 = -3k + 1

=> 4k = -2

=> k = -2/4

=> k = -1/2

From the given option value of k  =   -1/2

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