...

1. Select the start point of the line.
2. Select the tangent arc, circle, or ellipse, close to the point of tangency. The tangent line is created.

Anchor
1387 1387

Tan gent Line of Fixed Length

By default, Tangent to Arc creates a line from the start point, ending at the tangent object. To fix the length of the line, enter the length in the Inspector Bar and lock it, but do not press Enter. When you move the cursor, the line length remains constant.
Select the tangent object, close to the point of tangency. The fixed-length tangent line is created.