Determine the equation of the circle whose center C (-4, -3) that passes through (2, 1).

The number of arrangements of the letters K, I, N, D in a straight line is

Three-digit even numbers can be made using 5, 6, 7, 8 and 9.  The number of ways in which repetition digit is not allowed is

A parabola’s directrix is the line:

Which of the following is a general form of a parabola?

The unit vector in the opposite direction of       is

The directed values of two lines are and respectively. The angle between these lines is

If nonzero vectors and are perpendicular, then 

The equation of the plane which is parallel to zx-plane is

The point of intersection of zx-plane and the line whose equation is