# Thread: Circle Problem

1. ## Circle Problem

Helping my little brother's homework.

A circle of diameter 20cm has two parallel chords of length 8cm and 16cm.
Calculate the shortest distance between these chords.

Is the answer 8cm?

(sorry about awful drawing)

2. Originally Posted by r_maths
Helping my little brother's homework.

A circle of diameter 20cm has two parallel chords of length 8cm and 16cm.
Calculate the shortest distance between these chords.

Is the answer 8cm?

(sorry about awful drawing)
See attachment.

You are dealing with 2 different right triangles.

Calculate $x = \sqrt{100-16}=\sqrt{84}$

Calculate $y = \sqrt{100-64}=\sqrt{36}=6$

The distance between the parallels is:

$d = x-y = \sqrt{84}-6\approx 3.165...$