Question

Two circles with radii 5 cm and 3cm intersect each other at two points . the distance between their centres is 4 cm . Find the lenght of common chord.

Answer 1

AB is perndicular to oo' therefore, OAB and O'BA are right angle triangle
Oo'=4 ,oa=5 ,o'a=3
Let ab be x and ob be y therefore o'b=4-y
x*x+y*y=9 or x*x=9-y*y
X*x+16+y*y-8y=25
9-y*y+16+y*y-8y=25
-8y=0 or y=0
B and o' coincide
Therefore the length common chord is 6 cm