Two concentric circles with centre O have A,B,C,D as the points of intersection with the line l as shown in the figure. If AD=12cm and BC=8 cm, the length of AB,CD,AC and BD are respectively.
Draw a⊥OM to l
OM⊥BCandOM⊥AD
We know that perpendicular lines to a chord which pass through center bisect the chord
⟹BM=MC=12BC=4 cm
⟹AM=MD=12AD=6 cm
AB=CD=AM–BM=6–4=2 cm
AC=BD=AB+BC=2+8=10 cm