Question Details

Let C be a circle of radius 5 meters having center at O. Let PQ be a chord of C that passes through points A and B where A is located 4 meters north of O and B is located 3 meters east of O. Then, the length of PQ, in meters, is nearest to

Options

A

7.2

B

7.8

C

6.6

D

8.8

Show Answer

Correct Answer :

Option D

8.8

Solution :

The correct option is 8.8.

To find the length of the chord PQ, we can use a Cartesian coordinate system where the center of the circle O is placed at the origin (0,0).

Step 1: Write the equation of the circle.
Since the circle C has its center at O(0,0) and a radius of R=5 meters, its equation is:

x2 + y2 = 52 = 25

Step 2: Determine the coordinates of points A and B.
- Point A is located 4 meters north of O, which corresponds to the positive y-axis: A=(0,4).
- Point B is located 3 meters east of O, which corresponds to the positive x-axis: B=(3,0).

Step 3: Find the equation of the line passing through A and B.
The line passing through A(0,4) and B(3,0) represents the line containing the chord PQ.
Using the intercept form of a linear equation, we get:

x3 + y4 = 1
Multiplying the entire equation by 12 to clear the denominators gives:

4x + 3y - 12 = 0

Step 4: Calculate the perpendicular distance from the center O to the line.
The perpendicular distance d from the origin (0,0) to the line 4x+3y-12=0 is given by the formula:

d = |4(0)+3(0)-12| 42 + 32
Simplifying this expression yields:

d = 12 16+9 = 12 25 = 12 5 = 2.4 meters

Step 5: Determine the length of the chord PQ.
The length of a chord in a circle of radius R at a perpendicular distance d from the center is:

Length of PQ = 2 R2 - d2
Substituting R=5 and d=2.4 into the formula:

Length of PQ = 2 52 - (2.4)2
Length of PQ = 2 25 - 5.76 = 2 19.24
Estimating 19.244.386:

Length of PQ 2 × 4.386 8.772 meters
Rounding to the nearest option, the length of the chord PQ is nearest to 8.8.

Unlock Our Free Library

Access expert-curated educational resources and study materials—completely free.

Discover more resources

You may also like

Mock Tests

View All
  • CTET
  • intermediate
  • No time limit
  • child development and pedagogy, mathematics, social science

  • SSC
  • intermediate
  • 2 hours and 30 mins
  • child development and pedagogy, mathematics, social science

Ask AI Tutor
5 left
Q1 View Question & Options
AI Tutor is solving this question...
Reading question context & options...