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1
JEE Main 2021 (Online) 20th July Evening Shift
+4
-1
The lines x = ay $$-$$ 1 = z $$-$$ 2 and x = 3y $$-$$ 2 = bz $$-$$ 2, (ab $$\ne$$ 0) are coplanar, if :
A
b = 1, a$$\in$$R $$-$$ {0}
B
a = 1, b$$\in$$R $$-$$ {0}
C
a = 2, b = 2
D
a = 2, b = 3
2
JEE Main 2021 (Online) 20th July Evening Shift
+4
-1
Consider the line L given by the equation $${{x - 3} \over 2} = {{y - 1} \over 1} = {{z - 2} \over 1}$$. Let Q be the mirror image of the point (2, 3, $$-$$1) with respect to L. Let a plane P be such that it passes through Q, and the line L is perpendicular to P. Then which of the following points is on the plane P?
A
($$-$$1, 1, 2)
B
(1, 1, 1)
C
(1, 1, 2)
D
(1, 2, 2)
3
JEE Main 2021 (Online) 20th July Evening Shift
+4
-1
In a triangle ABC, if $$\left| {\overrightarrow {BC} } \right| = 3$$, $$\left| {\overrightarrow {CA} } \right| = 5$$ and $$\left| {\overrightarrow {BA} } \right| = 7$$, then the projection of the vector $$\overrightarrow {BA}$$ on $$\overrightarrow {BC}$$ is equal to
A
$${{19} \over 2}$$
B
$${{13} \over 2}$$
C
$${{11} \over 2}$$
D
$${{15} \over 2}$$
4
JEE Main 2021 (Online) 20th July Morning Shift
Let $$\overrightarrow a = 2\widehat i + \widehat j - 2\widehat k$$ and $$\overrightarrow b = \widehat i + \widehat j$$. If $$\overrightarrow c$$ is a vector such that $$\overrightarrow a .\,\overrightarrow c = \left| {\overrightarrow c } \right|,\left| {\overrightarrow c - \overrightarrow a } \right| = 2\sqrt 2$$ and the angle between $$(\overrightarrow a \times \overrightarrow b )$$ and $$\overrightarrow c$$ is $${\pi \over 6}$$, then the value of $$\left| {\left( {\overrightarrow a \times \overrightarrow b } \right) \times \overrightarrow c } \right|$$ is :
$${2 \over 3}$$
$${3 \over 2}$$