I have never seen this before. I know that a tangent line is perpendicular to a line drawn through the center of the circle at the point of tangency. A curriculum that I am reading states that :
"A tangent line is perpendicular to a circle at the point of tangency."
While I agree that the tangent line is perpendicular to the line that connects the center to the circle at the point of tangency, I cannot find any other reference that states that the line is perpendicular to the actual circle.
"A tangent line is perpendicular to a circle at the point of tangency."
While I agree that the tangent line is perpendicular to the line that connects the center to the circle at the point of tangency, I cannot find any other reference that states that the line is perpendicular to the actual circle.