JEE MAIN - Mathematics (2021 - 1st September Evening Shift - No. 9)
The distance of line $$3y - 2z - 1 = 0 = 3x - z + 4$$ from the point (2, $$-$$1, 6) is :
$$\sqrt {26} $$
$$2\sqrt 5 $$
$$2\sqrt 6 $$
$$4\sqrt 2 $$
Explanation
$$3y - 2z - 1 = 0 = 3x - z + 4$$
$$3y - 2z - 1 = 0$$
D.R's $$\Rightarrow$$ (0, 3, $$-$$2)
$$3x - z + 4$$ = 0
D.R's $$\Rightarrow$$ (3, $$-$$1, 0)
Let DR's of given line are a, b, c
Now, 3b $$-$$ 2c = 0 & 3a $$-$$ c = 0
$$\therefore$$ 6a = 3b = 2c
a : b : c = 3 : 6 : 9
Any point on line
3K $$-$$ 1, 6K + 1, 9K + 1
Now, 3(3K $$-$$ 1) + 6(6K + 1)1 + 9(9K + 1) = 0
$$\Rightarrow$$ K = $${1 \over 3}$$
Point on line $$\Rightarrow$$ (0, 3, 4)
Given point (2, $$-$$1, 6)
$$\Rightarrow$$ Distance = $$\sqrt {4 + 16 + 4} = 2\sqrt 6 $$
Option (c)
$$3y - 2z - 1 = 0$$
D.R's $$\Rightarrow$$ (0, 3, $$-$$2)
$$3x - z + 4$$ = 0
D.R's $$\Rightarrow$$ (3, $$-$$1, 0)
Let DR's of given line are a, b, c
Now, 3b $$-$$ 2c = 0 & 3a $$-$$ c = 0
$$\therefore$$ 6a = 3b = 2c
a : b : c = 3 : 6 : 9
Any point on line
3K $$-$$ 1, 6K + 1, 9K + 1
Now, 3(3K $$-$$ 1) + 6(6K + 1)1 + 9(9K + 1) = 0
$$\Rightarrow$$ K = $${1 \over 3}$$
Point on line $$\Rightarrow$$ (0, 3, 4)
Given point (2, $$-$$1, 6)
$$\Rightarrow$$ Distance = $$\sqrt {4 + 16 + 4} = 2\sqrt 6 $$
Option (c)
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