Let $$\overrightarrow u $$, $$\overrightarrow v $$ and $$\overrightarrow w $$ be vectors in three-dimensional space, where $$\overrightarrow u $$ and $$\overrightarrow v $$ are unit vectors which are not perpendicular to each other and $$\overrightarrow u $$ . $$\overrightarrow w $$ = 1, $$\overrightarrow v $$ . $$\overrightarrow w $$ = 1, $$\overrightarrow w $$ . $$\overrightarrow w $$ = 4
If the volume of the paralleopiped, whose adjacent sides are represented by the vectors, $$\overrightarrow u $$, $$\overrightarrow v $$ and $$\overrightarrow w $$, is $$\sqrt 2 $$, then the value of $$\left| {3\overrightarrow u + 5\overrightarrow v } \right|$$ is ___________.
Your Input ________
Answer
Correct Answer is 7
2
JEE Advanced 2021 Paper 1 Online
Numerical
Let $$\alpha$$, $$\beta$$ and $$\gamma$$ be real numbers such that the system of linear equations
x + 2y + 3z = $$\alpha$$
4x + 5y + 6z = $$\beta$$
7x + 8y + 9z = $$\beta$$ $$-$$ 1
is consistent. Let | M | represent the determinant of the matrix
Let P be the plane containing all those ($$\alpha$$, $$\beta$$, $$\gamma$$) for which the above system of linear equations is consistent, and D be the square of the distance of the point (0, 1, 0) from the plane P.
Let P be the plane containing all those ($$\alpha$$, $$\beta$$, $$\gamma$$) for which the above system of linear equations is consistent, and D be the square of the distance of the point (0, 1, 0) from the plane P.
Let $$\overrightarrow a = 2\widehat i + \widehat j - \widehat k$$ and $$\overrightarrow b = \widehat i + 2\widehat j + \widehat k$$ be two vectors. Consider a vector c = $$\alpha $$$$\overrightarrow a$$ + $$\beta $$$$\overrightarrow b$$, $$\alpha $$, $$\beta $$ $$ \in $$ R. If the projection of $$\overrightarrow c$$ on the vector ($$\overrightarrow a$$ + $$\overrightarrow b$$) is $$3\sqrt 2 $$, then the minimum value of ($$\overrightarrow c$$ $$-$$($$\overrightarrow a$$ $$ \times $$ $$\overrightarrow b$$)).$$\overrightarrow c$$ equals ................
Your Input ________
Answer
Correct Answer is 18
Explanation
Given vectors $$\overrightarrow a $$$$ = 2\widehat i + \widehat j - \widehat k$$
and $$\overrightarrow b = \widehat i + 2\widehat j + \widehat k$$
So, $$\overrightarrow a + \overrightarrow b = 3\widehat i + 3\widehat j \Rightarrow |\overrightarrow a + \overrightarrow b| = 3\sqrt 2 $$
Since, it is given that projection of $$\overrightarrow c $$ = $$\alpha $$a + $$\beta $$b on the vector ($$\overrightarrow a $$ + $$\overrightarrow b $$) is $$3\sqrt 2 $$, then
$${{(\overrightarrow a + \overrightarrow b ).\overrightarrow c } \over {|\overrightarrow a + \overrightarrow b|}} = 3\sqrt 2 $$
$$ \Rightarrow (\overrightarrow a + \overrightarrow b).(\alpha \overrightarrow a + \beta \overrightarrow b) = 18$$
$$ \Rightarrow \alpha (\overrightarrow a.\overrightarrow a) + \beta (\overrightarrow a.\overrightarrow b) + \alpha (\overrightarrow b.\overrightarrow a) + \beta (\overrightarrow a.\overrightarrow b) = 18$$