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Question

A circle of radius 4 cm is drawn inscribed in a right angle triangle ABC, right angled at C. If AC = 12 cm, then the value of CB is:

This question was previously asked in
SSC CGL 2023 (Tier-II) Paper 1 Previous Year Paper (26-Oct-2023) (Shift-1)
The correct answer is

16 cm

Given:

Radius of circle = 4 cm

AC = 12 cm;

∠ACB = 90°  

Concept used:

The tangent makes a right angle with the radius of a circle at the point of contact.

If two tangents are drawn from an external point of the circle, then they are equal in length.

Formula used:

Pythagoras theorem:

H2 = P2 + B2

Where, P = perpendicular; B = base;

H = hypotenuse

(a + b)2 = a2 + b+ 2ab

Calculation:

Quadrilateral PCRO is a square.

PC = CR = 4 cm

AR = (AC - CR) = (12 - 4) = 8 cm

AR = AQ = 8 cm

In △ABC

(AB)2 = (AC)2 + (BC)2

⇒ (8 + x)2 = 122 + (4 + x)2

⇒ 64 + x2 + 16x = 144 + 16 + x2 + 8x

⇒ 64  + 16x = 160  + 8x

⇒ 8x = (160 - 64) = 96

⇒ x = 96/8 = 12

BC = (4 + x) = 4 + 12 = 16 cm

∴ The correct answer is 16 cm. 

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Similar Questions

  1. A chord 21 cm long is drawn in a circle of diameter 25 cm. The perpendicular distance of the chord from the centre is:

  2. In a circle with radius 5 cm, a chord is at a distance of 3 cm from the centre. The length of the chord is:

  3. The distance between the centres of two circles is 24 cm. If the radius of the two circles are 4 cm and 8 cm, then what is the sum of the lengths (in cm) of the direct common tangent and the transverse common tangent?

  4. In a circle with centre O, an arc ABC subtends an angle of 132° at the center of the circle. Chord AB is produced to point P. Then ∠CBP is equal to∶

  5. What can be the maximum number of common tangent which can be drawn to two non-intersecting circles?

  6. There are two identical circles of radius 10 cm each. If the length of the direct common tangent is 26 cm, then what is the length (in cm) of the transverse common tangent?

  7. AB is a chord in the minor segment of a circle with centre O. C is a point on the minor arc (between A and B). The tangents to the circle at A and B meet at a point P. If ∠ACB = 108°, then ∠APB is equal to:

  8. AB is the chord of a circle such that AB = 10 cm. If the diameter of the circle is 20 cm, then the angle subtended by the chord at the centre is ________.

  9. Select the INCORRECT statement with respect to the properties of a circle.

  10. Radius of a circle is 5 cm. Length of chord AB in this circle is 6 cm. What is the distance of this chord from the centre of the circle?


Important Questions from Circles, Chords and Tangents

  1. A chord 21 cm long is drawn in a circle of diameter 25 cm. The perpendicular distance of the chord from the centre is:

  2. AB is a chord of a circle with centre O and P is any point on the circle. If ∠APB = 112°, then what is the measure of ∠OAB ?

  3. In a circle with radius 5 cm, a chord is at a distance of 3 cm from the centre. The length of the chord is:

  4. The distance between the centres of two circles is 24 cm. If the radius of the two circles are 4 cm and 8 cm, then what is the sum of the lengths (in cm) of the direct common tangent and the transverse common tangent?

  5. An equilateral triangle ABC and a scalene triangle DBC are inscribed in a circle on same side of the arc. what is ∠BDC equal to?

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