Math Problem Statement

Chords PQ and RS of a circle intersect at a point T at right angles to each other. If the segments PT, TQ and TS are of length 2, 6 and 3 units respectively then the diameter of the circle is

Solution

Given that chords PQPQ and RSRS of a circle intersect at point TT at right angles, and the segments PT=2PT = 2 units, TQ=6TQ = 6 units, and TS=3TS = 3 units, we are required to find the diameter of the circle.

Steps to Solve:

  1. Use the Power of a Point Theorem: The power of a point theorem states that if two chords ABAB and CDCD intersect at point TT inside a circle, then: PT×TQ=RT×TSPT \times TQ = RT \times TS

    For our problem: PT×TQ=RT×TSPT \times TQ = RT \times TS

    Substituting the given lengths: 2×6=RT×32 \times 6 = RT \times 3 12=3×RT12 = 3 \times RT RT=123=4 unitsRT = \frac{12}{3} = 4 \text{ units}

  2. Calculate the Lengths of the Chords:

    • PQ=PT+TQ=2+6=8PQ = PT + TQ = 2 + 6 = 8 units.
    • RS=RT+TS=4+3=7RS = RT + TS = 4 + 3 = 7 units.
  3. Use the Formula for the Lengths of the Chords: The lengths of the chords can be related to the radius RR of the circle using the formula: Length of chord=2R2d2\text{Length of chord} = 2 \sqrt{R^2 - d^2} where dd is the perpendicular distance from the center to the chord.

    Since the chords intersect at right angles at TT, and PQPQ and RSRS are perpendicular, we can apply Pythagoras’ theorem directly.

    R2=(PQ2)2+(RS2)2R^2 = \left(\frac{PQ}{2}\right)^2 + \left(\frac{RS}{2}\right)^2 Substituting: R2=(82)2+(72)2=42+3.52R^2 = \left(\frac{8}{2}\right)^2 + \left(\frac{7}{2}\right)^2 = 4^2 + 3.5^2 R2=16+12.25=28.25R^2 = 16 + 12.25 = 28.25 R=28.255.32 unitsR = \sqrt{28.25} \approx 5.32 \text{ units}

  4. Find the Diameter: The diameter DD is given by: D=2R=2×5.3210.64 unitsD = 2R = 2 \times 5.32 \approx 10.64 \text{ units}

Answer:

The diameter of the circle is approximately 10.64\boxed{10.64} units.


Do you have any questions, or would you like a more detailed explanation?

Related Questions:

  1. How would the solution change if the chords were not perpendicular?
  2. What is the Power of a Point theorem, and how is it applied in different scenarios?
  3. How do you find the radius if only one chord length is given?
  4. How can the center of the circle be found using the chords?
  5. What are other ways to find the diameter of a circle from intersecting chords?

Tip: Understanding the power of a point theorem is crucial as it often simplifies problems involving intersecting chords or tangents.

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Math Problem Analysis

Mathematical Concepts

Geometry
Circle Geometry
Pythagorean Theorem
Power of a Point Theorem

Formulas

Pythagorean theorem
Length of chord formula

Theorems

Power of a Point theorem

Suitable Grade Level

High School