JT is tangent to the circle and at the point of tangency, a right angle is formed. Angle T is a right angle. If angle J is the reference angle, side ET is opposite it measuring 3963. The hypotenuse of this right triangle is 3963+4.8 which is 3967.8. The trig identity that is the side opposite the reference angle over the hypotenuse is the sin ratio. Setting it up will look like this:
. That gives us that ∠J=.9987902616. Take the inverse sin of that on your calculator to find that ∠J=87.18° or 87.2°