Question 3
Two parallel chords of lengths and are on opposite sides of the centre of a circle. If the radius of the circle is , find the distance between the midpoints of the chords.
We will find the distance of each chord from the center. Then we will add these distances.
Step 1 — Distance of first chord
Let the first chord be . Its length is . The radius of the circle is . The perpendicular from the center bisects the chord. So, half the chord length is . Let be the distance from the center to chord . We use the Pythagorean theorem.

Step 2 — Distance of second chord
Let the second chord be . Its length is . The radius of the circle is . The perpendicular from the center bisects the chord. So, half the chord length is . Let be the distance from the center to chord . We use the Pythagorean theorem.

Step 3 — Total distance between midpoints
The chords are on opposite sides of the center. The distance between their midpoints is the sum of and .
Answer
The distance between the midpoints of the two chords is .
More questions in Exercise 5.3
Can you explain why the converse to Theorem 4 is true, i.e., why does the perpendicular from the centre of a circle to a chord of the circle bisect the chord?
(Hint: Use Fig. 5.12. You are told that . You need to show that .)
An isosceles triangle ABC is inscribed in a circle, with . Show that the altitude from A to BC passes through the centre of the circle.
Two parallel chords of lengths and are on opposite sides of the centre of a circle. If the radius of the circle is , find the distance between the midpoints of the chords.