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:

Number 1 = 17
number 2 = 72
number 3 = 24
work:
the three numbers are symbolized as x, y, and z
x + y + z = 113
number 2 (y) is 3 times the third number (z) so
y = 3z
so x + 3z + z = 113
the first number (x) is 7 less than than the third number (z) so
x = z - 7
so z -7 + 3z + z = 113
5z - 7 = 113
5z = 120
z = 24
x = 17
y = 72
Hope this helped :)
$450 since first month was free if it wasn’t free it would’ve been $495
Answer:
-10.5
Step-by-step explanation:
2 x (-5.25) = -10.5
To solve system of equations by substitution, we are going to use the first equation to substitute into the second equation wherever you see y.



_______________


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(rounded)
Next, substitute x = 3.29 into the first equation, or to any equation you'd like, to find y.




So, your final answer would be (3.29, 4.87).