Okay so you do not really need the circle equation. if you make a triangle with it's x length as 3 and it's y length as 4, you will be able to find the third length. Do Pythagorean theorem to find the hypotenuse.
the hypotenuse will be five after you calculate it.
sin is opposite over hypotenuse or Y over R
so... the sin is 4/5
make sure you know what quadrant your triangle is in for the negatives
So first you need your denominators to be the same so you can multiply. They share a common denominator of 24. 2/3 equals 16/24 and 2/8 equals 9/24. So now you need to turn your fractions into mixed numbers and multiply. Which equals 2112/576. That # is way to big so then you simplify and get 11/3. so now you have 5 and 1/6 divided by 11/3. So now just flip the second fraction multiply it by its reciprocal. 31/6 X 3/11=___. So your final answer is 1 and 9/22
"a" and integer is a whole number not a fraction or a decimal
If you are looking for the equation of the line,
Use Point Slope Form

y-4 = 3(x-1)
y-4 = 3x-3
y = 3x + 1