In your calculator, input arcsin(7/12). Make sure that your calculator is in degree mode. The answer is 35.69 degrees.
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:
12
Step-by-step explanation:
So, the 24cm, is the diameter, a little circle autonomy here, the diameter is the length across the circle, and the radius is to the mid point, or half-way point, which means that the radius is half the diameter, so, 24 ÷ 2 = 12
hope this helps:)