The
formula
, where r! is 1*2*3*...r
is the
formula which gives us the total number of ways of forming groups of r objects out of n objects.
for
example, given 10 objects, there are C(10,6) ways of forming groups of 6, out
of the 10 objects.
<span>Thus, there are C(6, 3) many ways of forming different triples out of 6.</span>

Answer: A.20
Answer:
the slope of the common cord is: 
Step-by-step explanation:
Given the focus (a,b) = (3,-28)
- for a parabola with directrix at x-axis the equation will be


- for a parabola with directrix at y-axis the equation will be


The common chord is the line between two points where the two parabolas intersect. For intersection, we can equate the two parabolas!
In other words, at the point of intersection of these two parabolas the values of the two parabolas will be the same.


we can now simplify the equation. (we can see that (x-3) and (y+28) both cancel out by -(x-3) and -(y+28))



this the equation of the common cord. but we need to select whether its
or
.
This can be found by realizing that the focus lies on the 4th quadrant of the xy-plane! And the equation
also generates a line that exists in the 2nd and 4th quadrant.
Hence the slope of the common cord is the slope of the line 
that is :
The answer is 20.77. You add 5.25+18.99+2.99+17.50=44.73. Then subtract 44.73 - 5.50 = 39.23. And then 60 - 39.23 = 20.77.
Answer:
The ships are 66 meters apart.
Step-by-step explanation:
For the sake of convenience, let us label ships A and B
As shown in the figure, the distances to the ships from right triangles.
The distance to the ship A is
and it is given by



And the distance to the ship B is
and is given by



Therefore, the distance
between the ships A and B is

In other words, the ships are 66 meters apart.