1
NDA Mathematics 14 November 2021
MCQ (Single Correct Answer)
+2.5
-0.83
Change Language
Let ABC be a triangle. If cos2A + cos2B + cos2C = -1 then which one of the following is correct?
A
sin A sin B sin C = 0
B
sin A sin B cos C = 0
C
cos A sin B sin C = 0
D
cos A cos B cos C = 0
2
NDA Mathematics 14 November 2021
MCQ (Single Correct Answer)
+2.5
-0.83
Change Language

What is the value of the following determinant?

$\begin{vmatrix} \cos \rm C & \tan \rm A & 0\\ \sin \rm B & 0 & -\tan \rm A\\ 0 & \sin \rm B & \cos \rm C \end{vmatrix}$

A
-1
B
0
C
2tan A sin B sin C
D
-2tan A sin B sin C
3
NDA Mathematics 14 November 2021
MCQ (Single Correct Answer)
+2.5
-0.83
Change Language
Suppose set A consists of first 250 natural numbers that are multiple of 3 and set B consists of first 200 even natural numbers. How many elements does A ∪ B have?
A
342
B
364
C
384
D
400
4
NDA Mathematics 14 November 2021
MCQ (Single Correct Answer)
+2.5
-0.83
Change Language
Let Sk denote the sum of first k terms of an AP. What is $\rm \frac{S_{30}}{S_{20}-S_{10}}$ equal to?
A
1
B
2
C
3
D
4
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