Answer:

Step-by-step explanation:
I assume that the three points given are the vertices of the triangle. So the three points are:
A (-4,1)
B (-7,5)
C (0,1)
The area of a triangle is given by:

where b is the base and h is the height.
Here we can take as follows:
- We can take the base to be the side AC, so that its length is equal to the distance between the two points:

- The height of the triangle is therefore the perpendicular distance between AC and point B. This is equivalent the difference in the x-coordinate between any point on AC and B, so:

Therefore, the area of the triangle is:

Answer:
7536 
Step-by-step explanation:
Given that:
Rate of decreasing of radius = 12 km/sec
Height of cylinder is fixed at = 2.5 km
Radius of cylinder = 40 km
To find:
The rate of change of Volume of the cylinder?
Solution:
First of all, let us have a look at the formula for volume of a cylinder.

Where
is the radius and
is the height of cylinder.
As per question statement:
= 40 km (variable)
= 2.5 (constant)

As
are constant:

Answer:
y=-1
Step-by-step explanation:
it is a straight line graph with no gradient therefore no X value. It crosses the y axis at -1
Apply slip and slide
a^2-3a-4
(a-4)(a+1)
(a-2)(2a+1)
Find zeros
a-2=0
a=2
2a+1=0
2a=-1
a=-1/2
Final answer: {-1/2, 2}