Answer:
Value of
Step-by-step explanation:
Given: A vertical line is dropped from the x-axis to the point (12, -9) as shown in the diagram below;
To find the value of
.
By definition of secants;

Now, first find the cosine of angle 
As the point (12 , -9) lies in the IV quadrant , where 
Consider a right angle triangle;
here, Adjacent side = 12 units and Opposite side = -9 units
Using Pythagoras theorem;

or

Cosine ratio is defined as in a right angle triangle, the ratio of adjacent side to hypotenuse side.

then;

and
therefore, the value of
is,