#### Topics

##### Number Systems

##### Algebra

##### Geometry

##### Trigonometry

##### Statistics and Probability

##### Coordinate Geometry

##### Mensuration

##### Internal Assessment

##### Real Numbers

##### Pair of Linear Equations in Two Variables

- Linear Equation in Two Variables
- Graphical Method of Solution of a Pair of Linear Equations
- Substitution Method
- Elimination Method
- Cross - Multiplication Method
- Equations Reducible to a Pair of Linear Equations in Two Variables
- Consistency of Pair of Linear Equations
- Inconsistency of Pair of Linear Equations
- Algebraic Conditions for Number of Solutions
- Simple Situational Problems
- Pair of Linear Equations in Two Variables
- Relation Between Co-efficient

##### Arithmetic Progressions

##### Quadratic Equations

- Quadratic Equations
- Solutions of Quadratic Equations by Factorization
- Solutions of Quadratic Equations by Completing the Square
- Nature of Roots of a Quadratic Equation
- Relationship Between Discriminant and Nature of Roots
- Situational Problems Based on Quadratic Equations Related to Day to Day Activities to Be Incorporated
- Application of Quadratic Equation

##### Polynomials

##### Circles

- Concept of Circle - Centre, Radius, Diameter, Arc, Sector, Chord, Segment, Semicircle, Circumference, Interior and Exterior, Concentric Circles
- Tangent to a Circle
- Number of Tangents from a Point on a Circle
- Concept of Circle - Centre, Radius, Diameter, Arc, Sector, Chord, Segment, Semicircle, Circumference, Interior and Exterior, Concentric Circles

##### Triangles

- Similar Figures
- Similarity of Triangles
- Basic Proportionality Theorem Or Thales Theorem
- Criteria for Similarity of Triangles
- Areas of Similar Triangles
- Right-angled Triangles and Pythagoras Property
- Similarity Triangle Theorem
- Application of Pythagoras Theorem in Acute Angle and Obtuse Angle
- Triangles Examples and Solutions
- Angle Bisector
- Similarity
- Ratio of Sides of Triangle

##### Constructions

##### Heights and Distances

##### Trigonometric Identities

##### Introduction to Trigonometry

##### Probability

##### Statistics

##### Lines (In Two-dimensions)

##### Areas Related to Circles

##### Surface Areas and Volumes

#### description

Theorem - The tangent at any point of a circle is perpendicular to the radius through the point of contact.

#### notes

In the previous section, you have seen that a tangent to a circle is a line that intersects the circle at only one point.

1) A circle can only have one tangent at a point of the cirlce.

But the circle is made of infinite numbers of points therefore a circle can have infinitely many tangents. But it can only have one tangent at one point.

#### theorem

Theorem1- The tangent at any point of a circle is perpendicular to the radius through the point of contact.

Given: A circle with centre O, a tangent XY at the point of contanct P.

To prove: OP ⊥ XY.

Construction: Take a point Q, other than P or XY. Jion OQ.

Proof: Q lies on the tangent XY.

Q lies outside the circle.

Let OQ cuts the circle at R.

OR < OQ (a part is less than a whole)

But, OR=OP (radii of the same circle)

So, OP < OQ

Thus, OP is shorter than any line segment joining O to any point on XY other than point P.

Therefore, OP is the shortest distance between O and line segment XY.

But, the shortest distance between a point and a line segment is the perpendicular distance.

Therefore, OP is perpendicular to XY.