To solve this problem, we will use the trigonometric function tangent. Recall that by definition in a right triangle:

In the given diagram, opposite leg=1 A.U. ( astronomical unit), θ=0.00001389°, and adjacent leg =d, therefore:

Solving the above equation for d, we get:

Simplifying, we get:

Answer:

For any star, if we are given an angle θ, we can use the following expression to determine its distance from the Sun:
