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NTA JEE Main 18th March 2021 Shift 2 - Mathematics

For the following questions answer them individually

Let the centroid of an equilateral triangle $$ABC$$ be at the origin. Let one of the sides of the equilateral triangle be along the straight line $$x + y = 3$$. If $$R$$ and $$r$$ be the radius of circumcircle and incircle respectively of $$\triangle ABC$$, then $$(R + r)$$ is equal to :

Let $$S_1 : x^2 + y^2 = 9$$ and $$S_2 : (x-2)^2 + y^2 = 1$$. Then the locus of center of a variable circle $$S$$ which touches $$S_1$$ internally and $$S_2$$ externally always passes through the points :

Let a tangent be drawn to the ellipse $$\frac{x^2}{27} + y^2 = 1$$ at $$(3\sqrt{3}\cos\theta, \sin\theta)$$ where $$\theta \in \left(0, \frac{\pi}{2}\right)$$. Then the value of $$\theta$$ such that the sum of intercepts on axes made by this tangent is minimum is equal to :

Consider a hyperbola $$H : x^2 - 2y^2 = 4$$. Let the tangent at a point $$P(4, \sqrt{6})$$ meet the x-axis at $$Q$$ and latus rectum at $$R(x_1, y_1)$$, $$x_1 > 0$$. If $$F$$ is a focus of $$H$$ which is nearer to the point $$P$$, then the area of $$\triangle QFR$$ (in sq. units) is equal to

If $$P$$ and $$Q$$ are two statements, then which of the following compound statement is a tautology?

Let in a series of $$2n$$ observations, half of them are equal to $$a$$ and remaining half are equal to $$-a$$. Also by adding a constant $$b$$ in each of these observations, the mean and standard deviation of new set become 5 and 20, respectively. Then the value of $$a^2 + b^2$$ is equal to :

A pole stands vertically inside a triangular park $$ABC$$. Let the angle of elevation of the top of the pole from each corner of the park be $$\frac{\pi}{3}$$. If the radius of the circumcircle of $$\triangle ABC$$ is 2, then the height of the pole is equal to :

Define a relation $$R$$ over a class of $$n \times n$$ real matrices $$A$$ and $$B$$ as "$$ARB$$" iff there exists a non-singular matrix $$P$$ such that $$PAP^{-1} = B$$. Then which of the following is true?

Let the system of linear equations
$$4x + \lambda y + 2z = 0$$
$$2x - y + z = 0$$
$$\mu x + 2y + 3z = 0$$, $$\lambda, \mu \in R$$
has a non-trivial solution. Then which of the following is true?

Let $$f : R \to R$$ be a function defined as
$$$f(x) = \begin{cases} \frac{\sin(a+1)x + \sin 2x}{2x}, & \text{if } x < 0 \\ b, & \text{if } x = 0 \\ \frac{\sqrt{x+bx^3} - \sqrt{x}}{bx^{5/2}}, & \text{if } x > 0 \end{cases}$$$
If $$f$$ is continuous at $$x = 0$$, then the value of $$a + b$$ is equal to :

Let $$g(x) = \int_0^x f(t)dt$$, where $$f$$ is continuous function in $$[0, 3]$$ such that $$\frac{1}{3} \le f(t) \le 1$$ for all $$t \in [0, 1]$$ and $$0 \le f(t) \le \frac{1}{2}$$ for all $$t \in (1, 3]$$.
The largest possible interval in which $$g(3)$$ lies is :

Let $$y = y(x)$$ be the solution of the differential equation $$\frac{dy}{dx} = (y+1)\left((y+1)e^{x^2/2} - x\right)$$, $$0 < x < 2.1$$, with $$y(2) = 0$$. Then the value of $$\frac{dy}{dx}$$ at $$x = 1$$ is equal to

Let $$\vec{a}$$ and $$\vec{b}$$ be two non-zero vectors perpendicular to each other and $$|\vec{a}| = |\vec{b}|$$, If $$|\vec{a} \times \vec{b}| = |\vec{a}|$$, then the angle between the vectors $$\left(\vec{a} + \vec{b} + (\vec{a} \times \vec{b})\right)$$ and $$\vec{a}$$ is equal to :

Let $$y = y(x)$$ be the solution of the differential equation $$xdy - ydx = \sqrt{(x^2 - y^2)}dx$$, $$x \ge 1$$, with $$y(1) = 0$$. If the area bounded by the line $$x = 1$$, $$x = e^\pi$$, $$y = 0$$ and $$y = y(x)$$ is $$\alpha e^{2\pi} + \beta$$, then the value of $$10(\alpha + \beta)$$ is equal to ___.

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Let $$P$$ be a plane containing the line $$\frac{x-1}{3} = \frac{y+6}{4} = \frac{z+5}{2}$$ and parallel to the line $$\frac{x-3}{4} = \frac{y-2}{-3} = \frac{z+5}{7}$$. If the point $$(1, -1, \alpha)$$ lies on the plane $$P$$, then the value of $$|5\alpha|$$ is equal to ___.

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