The whole secret of a successful life is to find out what is one’s destiny to do, and then do it. – **Henry Ford**

# Lecture - 1 Chapter 10 Circles

00:00:05 Meaning of Tangent and Secant Through a Circle

00:02:53 Point of Contact of Tangent

00:05:28 Proof of Radius is always Perpendicular to Tangent Theorem 10.1 : The tangent at any point of a circle is perpendicular to the radius through the point of contact.

00:14:02 NCERT Exercise 10.1 Question 1 How many tangents can a circle have?

00:14:52 NCERT Exercise 10.1 Question 2 Fill in the blanks :

(i) A tangent to a circle intersects it in ……………………..point (s).

(ii) A line intersecting a circle in two points is called a …………………

(iii) A circle can have …………….. parallel tangents at the most.

(iv) The common point of a tangent to a circle and the circle is called……………….

00:17:12 NCERT Exercise 10.1 Question 3 A tangent PQ at a point P of a circle of radius 5 cm meets a line through the centre O at a point Q so that OQ = 12 cm. Length PQ is :

00:20:12 NCERT Exercise 10.1 Question 4 Draw a circle and two lines parallel to a given line such that one is a tangent and the other, a secant to the circle.