AB is a line segment with P as midpoint. Three semicircles are drawn with AP,PB and AB as diameters. Another circle is drawn so as to touch all three semicircles. What’s the radius of this smaller circle?
Ans: b) 16AB.
Soln:
Let PB=r=PQ. QR=x. In triangle PRB, RB=2r-x. PR= r+x.
Since PRB is right angled, (r+x)2=(2r−x)2+r2 .
Solving we get x=r3=AB6