Math Problem Statement

B

Chap. 4.: Geometric Constructions

) Construct two concentric circles with centre 'O' with radii 3 cm and 5 cm. Construct tangent to a smaller circle from any point A on the larger circle. Measure and write the length of tangent segment. Calculate the length of tangent segment using Pythagoras theorem.

Solution

To solve this problem, we need to follow these steps:

Step-by-Step Solution:

  1. Draw Two Concentric Circles:

    • First, draw a point OO, which will serve as the center for both circles.
    • Draw a circle with radius 3cm3 \, \text{cm} centered at OO.
    • Then, draw another circle centered at OO with a radius of 5cm5 \, \text{cm}.
    • Now, you have two concentric circles: the smaller circle with radius 3cm3 \, \text{cm} and the larger circle with radius 5cm5 \, \text{cm}.
  2. Choose a Point on the Larger Circle:

    • Choose a point AA on the circumference of the larger circle (radius 5cm5 \, \text{cm}).
  3. Construct the Tangent from Point AA to the Smaller Circle:

    • Draw a line from AA to OO, which will serve as the radius to point AA.
    • Now, we need to draw a tangent from AA to the smaller circle, touching it at one point only. Let the point of tangency on the smaller circle be TT.
    • The line segment ATAT is the tangent to the smaller circle from AA.
  4. Calculate the Length of the Tangent Segment ATAT:

    • Since ATAT is tangent to the smaller circle from point AA, we can use the Pythagorean theorem to calculate its length.
    • In the right triangle AOT\triangle AOT:
      • OA=5cmOA = 5 \, \text{cm} (radius of the larger circle),
      • OT=3cmOT = 3 \, \text{cm} (radius of the smaller circle),
      • ATAT is the tangent we want to find.

    Using the Pythagorean theorem: AT=OA2OT2AT = \sqrt{OA^2 - OT^2} Substitute the values: AT=5232AT = \sqrt{5^2 - 3^2} AT=259AT = \sqrt{25 - 9} AT=16AT = \sqrt{16} AT=4cmAT = 4 \, \text{cm}

Answer:

  • The length of the tangent segment ATAT is 4cm4 \, \text{cm}.

Would you like further details on the construction steps or on applying the Pythagorean theorem here?


Related Questions:

  1. How would the length of the tangent change if the radii of the circles were doubled?
  2. Can you construct a tangent to the smaller circle from any point not on the larger circle?
  3. What would the tangent length be if the radius of the smaller circle was 4cm4 \, \text{cm} and the larger circle was 7cm7 \, \text{cm}?
  4. How can we verify that ATAT is perpendicular to the radius at point TT?
  5. What are some real-world applications of concentric circles and tangent lines?

Tip: When working with concentric circles, the radius difference can often reveal relationships about tangents and distances.

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Math Problem Analysis

Mathematical Concepts

Geometry
Circle Properties
Pythagorean Theorem

Formulas

AT = sqrt(OA^2 - OT^2)

Theorems

Pythagorean Theorem

Suitable Grade Level

Grades 6-8