Question 874874
Q: Find the length of a chord that is 15 cm from the center of a circle with a radius of 20 cm.
A:
In the figure below, a = 15, b = unknown and c = 20
*[illustration circle]
Using Pythagorean Theorem,
{{{a^2 + b^2 = c^2}}}
{{{15^2 + b^2 = 20^2}}}
{{{b = sqrt(20^2 - 15^2)}}} = {{{5*sqrt(7)}}} cm 
So the chord is 2b = {{{10*sqrt(7)}}} cm or 26.46 cm (approx)