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Given: In the figure, point A is in the exterior of the circle with centre P. AB is the tangent segment and secant through A intersects the circle in C and D.
To prove: AB2 = AC × AD
Construction: Draw segments BC and BD.
Write the proof by completing the activity.

Proof: In ΔABC and ΔADB,
∠BAC ≅ ∠DAB .....becuase ______
∠______ ≅ ∠______ ......[Theorem of tangent secant]
∴ ΔABC ∼ ΔADB .......By ______ test
∴ `square/square = square/square` .....[C.S.S.T.]
∴ AB2 = AC × AD
Proved.
Concept: Tangent and Secant Properties
In the figure, the centre of the circle is O and ∠STP = 40°.

- m (arc SP) = ? By which theorem?
- m ∠SOP = ? Give reason.
Concept: Inscribed Angle Theorem
Find the value of y, if the points A(3, 4), B(6, y) and C(7, 8) are collinear.
Concept: Circles Passing Through One, Two, Three Points
In the following figure, a quadrilateral LMNO circumscribes a circle with centre C. ∠O = 90°, LM = 25 cm, LO = 27 cm and MJ = 6 cm. Calculate the radius of the circle.

Concept: Tangent and Secant Properties
A pizza has 8 slices all equally spaced. Suppose pizza is a flat circle of radius 28 cm, find the area covered between 3 slices of pizza.
Concept: Secant and Tangent

In the above figure, ∠L = 35°, find :
- m(arc MN)
- m(arc MLN)
Solution :
- ∠L = `1/2` m(arc MN) ............(By inscribed angle theorem)
∴ `square = 1/2` m(arc MN)
∴ 2 × 35 = m(arc MN)
∴ m(arc MN) = `square` - m(arc MLN) = `square` – m(arc MN) ...........[Definition of measure of arc]
= 360° – 70°
∴ m(arc MLN) = `square`
Concept: Inscribed Angle Theorem

In the above figure, ∠ABC is inscribed in arc ABC.
If ∠ABC = 60°. find m ∠AOC.
Solution:
∠ABC = `1/2` m(arc AXC) ......`square`
60° = `1/2` m(arc AXC)
`square` = m(arc AXC)
But m ∠AOC = \[\boxed{m(arc ....)}\] ......(Property of central angle)
∴ m ∠AOC = `square`
Concept: Angle Subtended by the Arc to the Centre
Construct the circumcircle and incircle of an equilateral triangle ABC with side 6 cm and centre O. Find the ratio of radii of circumcircle and incircle.
Concept: Division of a Line Segment
Draw `angle ABC` of measure 80° and bisect it
Concept: Geometric Constructions
Draw ∠ABC of measures 135°and bisect it.
Concept: Geometric Constructions
∆AMT ~ ∆AHE. In ∆AMT, AM = 6.3 cm, ∠TAM = 50°, AT = 5.6 cm. `"AM"/"AH" = 7/5`. Construct ∆AHE.
Concept: Division of a Line Segment
∆ABC ~ ∆LBN. In ∆ABC, AB = 5.1 cm, ∠B = 40°, BC = 4.8 cm, \[\frac{AC}{LN} = \frac{4}{7}\]. Construct ∆ABC and ∆LBN.
Concept: Division of a Line Segment
Construct ∆PYQ such that, PY = 6.3 cm, YQ = 7.2 cm, PQ = 5.8 cm. If \[\frac{YZ}{YQ} = \frac{6}{5},\] then construct ∆XYZ similar to ∆PYQ.
Concept: Division of a Line Segment
Find the ratio in which point T(–1, 6)divides the line segment joining the points P(–3, 10) and Q(6, –8).
Concept: Division of a Line Segment
Find the co-ordinates of the points of trisection of the line segment AB with A(2, 7) and B(–4, –8).
Concept: Division of a Line Segment
If A(–14, –10), B(6, –2) is given, find the coordinates of the points which divide segment AB into four equal parts.
Concept: Division of a Line Segment
If A (20, 10), B(0, 20) are given, find the coordinates of the points which divide segment AB into five congruent parts.
Concept: Division of a Line Segment
The line segment AB is divided into five congruent parts at P, Q, R and S such that A–P–Q–R–S–B. If point Q(12, 14) and S(4, 18) are given find the coordinates of A, P, R, B.
Concept: Division of a Line Segment
Ponit M is the mid point of seg AB and AB = 14 then AM = ?
Concept: Geometric Constructions

Observe the adjoining figure and write down one pair of interior angles.
Concept: Geometric Constructions
