Algebra Questions (626)

Given \(\vec{a} = \hat{i} + 2\hat{j} + 4\hat{k}\), \(\vec{b} = \hat{i} + \lambda \hat{j} + 4\hat{k}\) and \(\vec{c} = 2\hat{i} + 4\hat{j} + (\lambda^2 - 1)\hat{k}\) are coplanar vectors. Find \(\vec{a} \times \vec{c}\).

The value of \(|(p + q)\cos\theta + r|\) is

The value of \begin{vmatrix} a \cdot p & b \cdot p & c \cdot p \\ a \cdot q & b \cdot q & c \cdot q \\ \cdot & \cdot & \cdot \end{vmatrix} is

Let ABCD be a parallelogram such that AB = q, AD = p and ∠BAD be an acute angle. If r is the vector that coincides with the altitude directed from the vertex B to the side AD, then r is given by

Let \(\vec{a}\), \(\vec{b}\) and \(\vec{c}\) be three unit vectors such that \(\vec{a}\times(\vec{b}\times\vec{c})=\dfrac{\sqrt{3}}{2}(\vec{b}+\vec{c})\). If \(\vec{b}\) is not parallel to \(\vec{c}\), then the angle between \(\vec{a}\) and \(\vec{b}\) is

Let \(\vec{b} = x\hat{i} + y\hat{j} + z\hat{k}\). It is given that \(\vec{a} \times \vec{b} + \vec{c} = 0\), \(\vec{c} = -\vec{a} \times \vec{b} = \vec{b} \times \vec{a}\), and \(\vec{c}\) is normal to \(\vec{b}\). Also \(\vec{a} \cdot \vec{b} = 3\). Then \(\vec{b}\) is:

P is the point of intersection of the diagonals of the parallelogram ABCD. If O is any point, then $\vec{OA} + \vec{OB} + \vec{OC} + \vec{OD}$ is equal to

Ex. 96 Statement I: If a is perpendicular to b and c, then a × (b × c) = 0Statement II: If b is perpendicular to c, then b × c = 0

We have \((2\vec{a} - \vec{b}) \cdot [(\vec{a} \times \vec{b}) \times (\vec{a} + 2\vec{b})]\). If \(|\vec{a}| = 1\), \(|\vec{b}| = 1\), \(\vec{a} \cdot \vec{b} = 1\), find the value of the expression.

Ex. 53 In parallelogram ABCD, M is a point on DC which divides DC in the ratio 1 : 2 and AM intersects BD at Q. Point Q divides DB in the ratio

The final resultant displacement of the ant is:

Direction of the ant's resultant displacement is :

Ex. 109: If AP, BQ and CR are the altitudes of acute \triangle ABC and 9\overrightarrow{AP} + 4\overrightarrow{BQ} + 7\overrightarrow{CR} = \mathbf{0}, then \angle ACB is equal to

Example 29. The position vectors of the vertices A, B and C of a triangle are \(\vec{i} - \vec{j} - 3\vec{k}\), \(2\vec{i} + \vec{j} - 2\vec{k}\) and \(-5\vec{i} + 2\vec{j} - 6\vec{k}\), respectively. The length of the bisector AD of the \(\angle BAC\), where D is on the segment BC, is

If \(\vec{a} = \dfrac{1}{\sqrt{10}}(3\hat{i} + \hat{k})\) and \(\vec{b} = \dfrac{1}{7}(2\hat{i} + 3\hat{j} - 6\hat{k})\), then the value of \((2\vec{a} - \vec{b}) \cdot [(\vec{a} \times \vec{b}) \times (\vec{a} + 2\vec{b})]\) is

If AB AC AB × AC = λ AE AG AE × AG, then the value of λ is:

The volume of the parallelepiped whose coterminous edges are represented by the vectors $2\mathbf{b} \times \mathbf{c}$, $3\mathbf{c} \times \mathbf{a}$ and $4\mathbf{a} \times \mathbf{b}$ where $\mathbf{a} = (1 + \sin \theta)\mathbf{i} + \cos \theta \mathbf{j} + \sin 2\theta \mathbf{k}$, $\mathbf{b} = \sin\left(\theta + \frac{2\pi}{3}\right)\mathbf{i} + \cos\left(\theta + \frac{2\pi}{3}\right)\mathbf{j} + \sin\left(2\theta + \frac{4\pi}{3}\right)\mathbf{k}$, $\mathbf{c} = \sin\left(\theta - \frac{2\pi}{3}\right)\mathbf{i} + \cos\left(\theta - \frac{2\pi}{3}\right)\mathbf{j} + \sin\left(2\theta - \frac{4\pi}{3}\right)\mathbf{k}$ is 18 cubic units, then the value of $\theta$ in the interval $\left(0, \frac{\pi}{2}\right)$ is:

Ex. 22 If a, b, c be non-zero vectors such that a is perpendicular to b and c and \(|\mathbf{a}| = 1\), \(|\mathbf{b}| = 2\), \(|\mathbf{c}| = 1\), \(\mathbf{b} \cdot \mathbf{c} = 1\) and there is a non-zero vector d coplanar with \(\mathbf{a} + \mathbf{b}\) and \(2\mathbf{b} - \mathbf{c}\) and \(\mathbf{d} \cdot \mathbf{a} = 1\), then minimum value of \(|\mathbf{d}|\) is

If a, b and c are three non-coplanar uni-modular vectors, each inclined with other at an angle 30°, then volume of tetrahedron whose edges are a, b and c is

If [a × b b × c c × a] = λ[a b c]², then λ is equal to

Let \(\vec{a}=\hat{i}-\hat{j}\), \(\vec{b}=\hat{i}+\hat{j}+\hat{k}\) and \(\vec{c}\) be a vector such that \(\vec{a}\times\vec{c}+\vec{b}=\vec{0}\) and \(\vec{a}\cdot\vec{c}=4\), then \(|\vec{c}|^2\) is equal to:

The least positive integral value of $\alpha$, for which the angle between the vectors $\alpha\hat{i}-2\hat{j}+2\hat{k}$ and $\alpha\hat{i}+2\alpha\hat{j}-2\hat{k}$ is acute, is ___.

Let $\vec{a}=3\hat{i}+\hat{j}-2\hat{k}$, $\vec{b}=4\hat{i}+\hat{j}+7\hat{k}$ and $\vec{c}=\hat{i}-3\hat{j}+4\hat{k}$. If a vector $\vec{p}$ satisfies $\vec{p}\times\vec{b}=\vec{c}\times\vec{b}$ and $\vec{p}\cdot\vec{a}=0$, then $\vec{p}\cdot(\hat{i}-\hat{j}-\hat{k})$ is equal to:

If three points A, B and C have position vectors \((1, x, 3)\), \((3, 4, 7)\) and \((y, -2, -5)\) respectively and if they are collinear, then \((x, y)\) is equal to

Consider three vectors $\vec{a},\vec{b},\vec{c}$. Let $|\vec{a}|=2$, $|\vec{b}|=3$ and $\vec{a}=\vec{b}\times\vec{c}$. If $\alpha\in\left[0,\dfrac{\pi}{3}\right]$ is the angle between the vectors $\vec{b}$ and $\vec{c}$, then the minimum value of $27|\vec{c}-\vec{a}|^2$ is equal to:

Let position vectors of $A,B,C,D$ be $5\hat{i}+5\hat{j}+2\lambda\hat{k}$, $\hat{i}+2\hat{j}+3\hat{k}$, $-2\hat{i}+\lambda\hat{j}+4\hat{k}$ and $-\hat{i}+5\hat{j}+6\hat{k}$. Let $S=\{\lambda\in\mathbb{R}: A,B,C,D\text{ coplanar}\}$. Then $\sum_{\lambda\in S}(\lambda+2)^2$ is equal to

Coterminous edges $\vec{a},\vec{b},\vec{c}$ form parallelepiped of volume $V$. Volume with edges $\vec{a},\vec{b}+\vec{c},\vec{a}+2\vec{b}+3\vec{c}$ is equal to

For $\vec{a}=a_1\hat{i}+a_2\hat{j}+a_3\hat{k}$ with $10|a_i|<1$: (A) $\max|a_i|\leq|\vec{a}|$ and (B) $|\vec{a}|\leq3\max|a_i|$

Let $\lambda\in\mathbb{Z}$, $\vec{a}=\lambda\hat{i}+\hat{j}-\hat{k}$. If $|\vec{a}\times(2\hat{i}-\hat{j}+\hat{k})|^2+...$

$S$ = set of $(\lambda,\mu)$ for which $\lambda\hat{i}-\hat{j}+\hat{k}$, $\hat{i}+2\hat{j}+\mu\hat{k}$, $3\hat{i}-4\hat{j}+5\hat{k}$ coplanar, $\lambda-\mu=5$. Then $\sum_{S}80(\lambda^2+\mu^2)$ is equal to

$ABCD$ quadrilateral, $E,F$ midpoints of $AC,BD$. $(\overrightarrow{AB}-\overrightarrow{BC})+(\overrightarrow{AD}-\overrightarrow{DC})=k\overrightarrow{FE}$. Then $k$ is equal to

$|\vec{a}|=2$, $|\vec{b}|=3$, angle between $\vec{a},\vec{b}=\frac{\pi}{4}$. Then $|(\vec{a}+2\vec{b})\times(2\vec{a}-3\vec{b})|^2$ is equal to

Let $\vec{a}=6\hat{i}+\hat{j}-\hat{k}$ and $\vec{b}=\hat{i}+\hat{j}$. If $\vec{c}$ is a vector such that $|\vec{c}|\geq6$, $\vec{a}\cdot\vec{c}=6|\vec{c}|$, $|\vec{c}-\vec{a}|=2\sqrt{2}$ and the angle between $\vec{a}\times\vec{b}$ and $\vec{c}$ is $60^\circ$, then $|(\vec{a}\times\vec{b})\times\vec{c}|$ is equal to:

For any vector \(\vec{a}=a_1\hat{i}+a_2\hat{j}+a_3\hat{k}\) with \(10|\vec{a}|\geq1\), consider: (A) \(|\vec{a}\times\hat{i}|^2+|\vec{a}\times\hat{j}|^2+|\vec{a}\times\hat{k}|^2=2|\vec{a}|^2\). (B) \(|\vec{a}\cdot\hat{i}|^2+|\vec{a}\cdot\hat{j}|^2+|\vec{a}\cdot\hat{k}|^2=|\vec{a}|^2\). Which is true?

Let $\vec{a}=2\hat{i}+\alpha\hat{j}+\hat{k}$, $\vec{b}=-\hat{i}+\hat{k}$, $\vec{c}=\beta\hat{j}-\hat{k}$, where $\alpha$ and $\beta$ are integers and $\alpha\beta=-6$. Let the values of the ordered pair $(\alpha,\beta)$, for which the area of the parallelogram of diagonals $\vec{a}+\vec{b}$ and $\vec{b}+\vec{c}$ is $\dfrac{\sqrt{21}}{2}$, be $(\alpha_1,\beta_1)$ and $(\alpha_2,\beta_2)$. Then $\alpha_1^2+\beta_1^2-\alpha_2\beta_2$ is equal to

For $\lambda>0$, let $\theta$ be the angle between the vectors $\vec{a}=\hat{i}+\lambda\hat{j}-3\hat{k}$ and $\vec{b}=3\hat{i}-\hat{j}+2\hat{k}$. If the vectors $\vec{a}+\vec{b}$ and $\vec{a}-\vec{b}$ are mutually perpendicular, then the value of $(14\cos\theta)^2$ is equal to

Let $\vec{a}=\hat{i}+2\hat{j}+3\hat{k}$, $\vec{b}=2\hat{i}+3\hat{j}-5\hat{k}$ and $\vec{c}=3\hat{i}-\hat{j}+\lambda\hat{k}$ be three vectors. Let $\vec{r}$ be a unit vector along $\vec{b}+\vec{c}$. If $\vec{r}\cdot\vec{a}=3$, then $3\lambda$ is equal to:

Let \(\vec{a},\vec{b}\) be two non-zero non-collinear vectors. Then \(|\vec{a}\times\vec{b}|\) equals

Let \to ^ ^ ^ a = 3 i - j + 2k, \to ^ ^ b = a \times ( i - 2k) and \to ^ c = b \times k . Then the projection of \to ^ c - 2j \to is : on a

Let a = 2 ^i - ^j + 3 k^ , b = 3 ^i - 5 ^j + k^ and c be a vector such that a \times c = c \times b and ​ ​ ( a + c ) ⋅ ( b + c ) = 168. Then the maximum value of ∣ c ∣ 2 is :

The point having position vectors 2i + 3j + 4k, 3i + 4j + 2k and 4i + 2j + 3k are the vertices of

Let $\vec{a}$ and $\vec{b}$ be two vectors such that $|\vec{b}|=1$ and $|\vec{b}\times\vec{a}|=2$. Then $|(\vec{b}\times\vec{a})-\vec{b}|^2$ is equal to:

Let $\vec{a}=a_1\hat{i}+a_2\hat{j}+a_3\hat{k}$ and $\vec{b}=b_1\hat{i}+b_2\hat{j}+b_3\hat{k}$ be two vectors such that $|\vec{a}|=1$, $\vec{a}\cdot\vec{b}=2$ and $|\vec{b}|=4$. If $\vec{c}=2(\vec{a}\times\vec{b})-3\vec{b}$, then the angle between $\vec{b}$ and $\vec{c}$ is equal to:

Let $\vec{a}$ and $\vec{b}$ be two vectors such that $|\vec{a}|=1$, $|\vec{b}|=4$ and $\vec{a}\cdot\vec{b}=2$. If $\vec{c}=(2\vec{a}\times\vec{b})-3\vec{b}$ and the angle between $\vec{b}$ and $\vec{c}$ is $\alpha$, then $192\sin^2\alpha$ is equal to _____.

Let $\vec{a}=\hat{i}+\hat{j}+\hat{k}$, $\vec{b}=2\hat{i}+4\hat{j}-5\hat{k}$ and $\vec{c}=x\hat{i}+2\hat{j}+3\hat{k}$, $x\in\mathbb{R}$. If $\vec{d}$ is the unit vector in the direction of $\vec{b}+\vec{c}$ such that $\vec{a}\cdot\vec{d}=1$, then $(\vec{a}\times\vec{b})\cdot\vec{c}$ is equal to

Let $ABC$ be a triangle of area $15\sqrt{2}$ and the vectors $\overrightarrow{AB}=\hat{i}+2\hat{j}-7\hat{k}$, $\overrightarrow{BC}=a\hat{i}+b\hat{j}+c\hat{k}$ and $\overrightarrow{AC}=6\hat{i}+d\hat{j}-2\hat{k}$, $d>0$. Then the square of the length of the largest side of the triangle $ABC$ is _____

If $A(3,1,-1)$, $B\left(\dfrac{5}{3},\dfrac{7}{3},\dfrac{1}{3}\right)$, $C(2,2,1)$ and $D\left(\dfrac{10}{3},\dfrac{2}{3},-\dfrac{1}{3}\right)$ are the vertices of a quadrilateral $ABCD$, then its area is

The set of all $\alpha$, for which the vectors $\vec{a}=\alpha t\hat{i}+6\hat{j}-3\hat{k}$ and $\vec{b}=t\hat{i}-2\hat{j}-2\alpha t\hat{k}$ are inclined at an obtuse angle for all $t\in\mathbb{R}$, is

In an isosceles triangle \(ABC\) with \(AB=AC\), M is the midpoint of \(BC\). Given an equilateral triangle with side \(\vec{a}\), the scalar triple product \([\vec{a},\vec{b},\vec{c}]\) (where \(\vec{a},\vec{b},\vec{c}\) are sides) equals

Let \(f : R \to (0, 1)\) be a continuous function, then which of the following pair of vectors are linearly dependent for some \(x \in (0, 1)\)?