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1
JEE Main 2021 (Online) 16th March Morning Shift
+4
-1
If for a > 0, the feet of perpendiculars from the points A(a, $$-$$2a, 3) and B(0, 4, 5) on the plane lx + my + nz = 0 are points C(0, $$-$$a, $$-$$1) and D respectively, then the length of line segment CD is equal to:
A
$$\sqrt {41}$$
B
$$\sqrt {55}$$
C
$$\sqrt {31}$$
D
$$\sqrt {66}$$
2
JEE Main 2021 (Online) 26th February Evening Shift
+4
-1
If the mirror image of the point (1, 3, 5) with respect to the plane

4x $$-$$ 5y + 2z = 8 is ($$\alpha$$, $$\beta$$, $$\gamma$$), then 5($$\alpha$$ + $$\beta$$ + $$\gamma$$) equals :
A
39
B
41
C
47
D
43
3
JEE Main 2021 (Online) 26th February Evening Shift
+4
-1
If vectors $$\overrightarrow {{a_1}} = x\widehat i - \widehat j + \widehat k$$ and $$\overrightarrow {{a_2}} = \widehat i + y\widehat j + z\widehat k$$ are collinear, then a possible unit vector parallel to the vector $$x\widehat i + y\widehat j + z\widehat k$$ is :
A
$${1 \over {\sqrt 3 }}\left( {\widehat i - \widehat j + \widehat k} \right)$$
B
$${1 \over {\sqrt 2 }}\left( { - \widehat j + \widehat k} \right)$$
C
$${1 \over {\sqrt 2 }}\left( {\widehat i - \widehat j} \right)$$
D
$${1 \over {\sqrt 3 }}\left( {\widehat i + \widehat j - \widehat k} \right)$$
4
JEE Main 2021 (Online) 26th February Evening Shift
+4
-1
Let L be a line obtained from the intersection of two planes x + 2y + z = 6 and y + 2z = 4. If point P($$\alpha$$, $$\beta$$, $$\gamma$$) is the foot of perpendicular from (3, 2, 1) on L, then the
value of 21($$\alpha$$ + $$\beta$$ + $$\gamma$$) equals :
A
102
B
142
C
136
D
68
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