Consider the following statements:
1. In a triangle $ABC$, if $\cot A \cdot \cot B \cdot \cot C>0$, then the triangle is an acute-angled triangle.
2. In a triangle $ABC$, if $\tan A \cdot \tan B \cdot \tan C > 0$, then the triangle is an obtuse-angled triangle.
Which of the statements given above is/are correct?
1 only
2 only
Both 1 and 2
Neither 1 nor 2
If (a, b) is the centre and c is the radius of the circle $x^2 + y^2 + 2x + 6y + 1 = 0$, then what is the value of $a^2 + b^2 + c^2$?
19
18
17
11
If (1, −1, 2) and (2, 1, −1) are the end points of a diameter of a sphere $x^2 + y^2 + z^2 + 2ux + 2vy + 2wz − 1 = 0$, then what is $u + v + w$ equal to?
−2
−1
1
2
The number of points represented by the equation $x = 5$ on the $xy$-plane is
Zero
One
Two
Infinitely many