Study Materials and Revision Notes for Ch 10 Circle Class 10th Maths
Circle• Circle: A circle is a locus of a point which moves in such a way that the distance from that point is always fixed.
• Radius: The constant distance from the centre to the circumference of the circle.
• Secant: A line which intersect the circle at two different points.
• Chord: Any line segment joining the two points on the circumference of the circle.
• Diameter: The longest distance between the two points on the circumference of the circle. It is the longest chord.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhgbFnRubhrz2MzgFbzCgMh5Cwg7kePuod6potm1ULZwTfPPi9ltCrT8sAVFAmP3wJXC0jCYai8U5p_sqOKi4Z-ddU5DHznh_TMSORFueM4VmAu1i-HWPOcSIRbDBNvhCh1qtBjCxvsEmw/s1600-rw/circle-class-10-notes-1.jpg)
Here, AO is the radius of the circle and AB is the diameter of the circle.
Tangent
• Tangent: A line which touches the circle exactly at one point.
• A line which touches the circle exactly at one point.
• The tangent at any point on a circle is perpendicular to the radius through the point of contact.
• In the above diagram l is tangent to the circle at point P. O is center, Then OP is perpendicular to l.
OP ⊥ l.
Tangent drawn from an external point to a circle
Length of the tangent: The length of the segment of the tangent from an external point P to the point of contact with the circle is called the length of the tangent from the point P to the circle.
Theorem: The lengths of tangents drawn from an external point to a circle are equal.
Two tangents are drawn from a point P, PA and PB.
PA=PB.