ස්පර්ශක — සා/පෙළ ගණිතය

A tangent is a straight line that touches a circle at exactly one point. This point is called the point of tangency. The tangent line does not cross the interior of the circle; it just touches the circumference at that single point. Understanding tangents is crucial for solving geometry problems involving circles, especially in the context of the Grade 11 O/L examination.

The most fundamental property of a tangent is that it is perpendicular to the radius drawn to the point of tangency. That is, if a line is tangent to a circle at point P, and O is the centre of the circle, then the radius OP is perpendicular to the tangent line at P. This is a theorem that is always true and is the basis for many other results.