Question 898836
7*cot(270) = 0


3*cos(180) = -3


7*cot(270) - 3*cos(180) is equal to 0 + 3 which is equal to 3.


that's your solution.


i used a calculator.
if i didn't have a calculator, i would do the following.



reference angle for 270 degrees is equal to 90 because 180 + 90 = 270.
cot(90) = cos(90)/sin(90) = 0/1 = 0.
cot(90) = 0
270 is in between the third and fourth quadrant.
since the cotangent is equal to 0, the sign doesn't matter, so cot(270) = 0.


reference angle for 180 is equal to 0 because 180 - 180 = 0.
cos(0) = 1
180 degrees is between second and third quadrant.
cosine is negative when the angle is in between the second and third quadrant, so cos(180) = -1


therefore:


7*cot(270) - 3*cos(180) = 7*0 -  3*(-1) which is equal to 0 + 3 which is equal to 3.


the graphs of cot(270) and cos(180) are shown below:


<img src="http://theo.x10hosting.com/2014/090706.jpg" alt="$$$" </>


<img src="http://theo.x10hosting.com/2014/090707.jpg" alt="$$$" </>