Answer:
a) For this case we can use the fact that 
And for this case since we ar einterested on
and we know that the if we are below the y axis the sine would be negative then:

b) From definition we can use the fact that
and we got this:

We can use the notabl angle
and we know that :

Then we know that
correspond to 225 degrees and that correspond to the III quadrant, and we know that the sine and cosine are negative on this quadrant. So then we have this:

Step-by-step explanation:
For this case we can use the notable angls given on the picture attached.
Part a
For this case we can use the fact that 
And for this case since we ar einterested on
and we know that the if we are below the y axis the sine would be negative then:

Part b
From definition we can use the fact that
and we got this:

We can use the notabl angle
and we know that :

Then we know that
correspond to 225 degrees and that correspond to the III quadrant, and we know that the sine and cosine are negative on this quadrant. So then we have this:

Answer:
It would take the newer pump 4.5 hours to drain the pool
Step-by-step explanation:
Let's investigate first what is the fraction of the job done in the unit of time (hour in this case) by each pump if the work individually:
older pump: if it takes it 9 hours to complete the job, it does
of the job in one hour.
newer pump: we don't know how long it takes (this is our unknown) so we call it "x hours". Therefore, in the unit of time (in one hour) it would have completed
of the total job.
both pumps together: since it takes both 3 hours to complete the job, in one hour they do
of the job.
Now, we can write the following equation about fractions of the job done:
<em>The fraction of the job done by the older pump plus the fraction of the job done by the newer pump in one hour should total the fraction of the job done when they work together.</em> That is in mathematical terms:

and solving for x:

Answer:
10 is the answer
Step-by-step explanation:
You add 3 to 4 getting 7. Adding 3 to 7 gets you 10
There is something wrong with drawing. IC intercepts with AB at A.