The answer is A which is 125
These are right triangles that will use either sin, cos, or tan, depending upon what you have to work with in regards to the reference angle. The first one has a reference angle of 51 with y being the side opposite it and 12 being the hypotenuse. The sin identity uses the side opposite over the hypotenuse as its formula:

and 12 sin(51) = y and y = 9.325
The second one has the reference angle as the unknown. You could use any of the identities here because you have all the sides of the triangle, but I will use sin again:

and

and

The next one has a referece angle of 13 with 24 being the side adjacent to it and the unknown being the side across from it. You will use the tangent identity here:

and 24 tan(13) = x so x = 5.540
The last one has a reference angle of 20 with the hypotenuse as the unknown x, and the side across from it as 10. Use the sin identity again:

and

and

with x = 29.238
Everything is in regards to the reference angle; you HAVE to be able to identify the reference angle and then how the given sides are related to it.
Answer:
y = 3x + 6
Step-by-step explanation:
y2 - y1 / x2 - x1
9 - (-6) / 1 - (-4)
15/5
= 3
y = 3x + b
9 = 3(1) + b
9 = 3 + b
6 = b
The cosine repeats itself every 360 degrees, and it mirrors at 0 and 180 degrees. It inverts around 90 and 270.
So without using a calculator, you can tell that:
cos(520)=cos(520-360)=cos(160)
cos(160) = cos(180-20) = cos(180+20) = cos(200)
cos(160) is NOT equal to cos(20), it would be -cos(20).
cos(160) = -cos(20) = -cos(-20)
So C is the only one unequal.