Question 1180406
Water is flowing through a pipe with radius 14 cm.
 The maximum depth of the water is 9 cm. 
 What is the width, PQ, of the surface of the water?
:
Draw this out, you will see that the chord PQ is: 14-9 = 5 cm from the center
draw the radii to P & Q, and a line from the center to the middle of the chord.
two right triangles are formed which we can use pythag to solve.
Let a = half the length of the chord
a^2 + 5^2 = 14^2
a^2 + 25 = 196
a^2 = 196 - 25
a^2 = 171
a = {{{sqrt(171)}}}
a = 13.0767
PQ = 2 * 13.0767
PQ = 26.534 cm