1
WB JEE 2021
MCQ (Single Correct Answer)
+2
-0.5
Change Language
The plane lx + my = 0 is rotated about its line of intersection with the plane z = 0 through an angle $$\alpha$$. The equation changes to
A
$$lx + my \pm \tan \alpha \sqrt {{l^2} + {m^2}} = 0$$
B
$$lx + my \pm z\tan \alpha \sqrt {{l^2} + {m^2} + 1} = 0$$
C
$$lx + my \pm z\tan \alpha \sqrt {{l^2} + 1} = 0$$
D
$$lx + my \pm z\tan \alpha \sqrt {{l^2} + {m^2}} = 0$$
2
WB JEE 2021
MCQ (Single Correct Answer)
+2
-0.5
Change Language
The points of intersection of two ellipses $${x^2} + 2{y^2} - 6x - 12y + 20 = 0$$ and $$2{x^2} + {y^2} - 10x - 6y + 15 = 0$$ lie on a circle. The centre of the circle is
A
(8, 3)
B
(8, 1)
C
$$\left( {{8 \over 3},3} \right)$$
D
(3, 8)
3
WB JEE 2021
MCQ (Single Correct Answer)
+2
-0.5
Change Language
Let $$I = \int_{\pi /4}^{\pi /3} {{{\sin x} \over x}dx} $$. Then
A
$${{\sqrt 3 } \over 8} \le I \le {{\sqrt 2 } \over 6}$$
B
$${{\sqrt 3 } \over {2\pi }} \le I \le {{2\sqrt 3 } \over \pi }$$
C
$${{\sqrt 3 } \over 9} \le I \le {{\sqrt 2 } \over {16}}$$
D
$$\pi \le I \le {{4\pi } \over 3}$$
4
WB JEE 2021
MCQ (More than One Correct Answer)
+2
-0
Change Language
If $$\left| {z + i} \right| - \left| {z - 1} \right| = \left| z \right| - 2 = 0$$ for a complex number z, then z is equal to
A
$$\sqrt 2 (1 + i)$$
B
$$\sqrt 2 (1 - i)$$
C
$$\sqrt 2 ( - 1 + i)$$
D
$$\sqrt 2 ( - 1 - i)$$
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