In the given figure, if AB = 10 cm, CD = 7 cm, SD = 4 cm and AS = 5 cm, then BC = ?

8 cm

From a common point tangents drawn on a circle is of same length.

SD = DR , CR = CQ , BQ = BP & AP = AS

AB = 10 cm, CD = 7 cm, SD = 4 cm and AS = 5 cm

⇒ SD = 4 cm & SD = DR

⇒ DR = 4 cm

It is given that , CD = 7 cm

CR = 7 - 4 = 3 cm

⇒ CR = CQ

⇒  CQ = 3 cm

We know,

AS = 5 cm

AS = AP = 5 cm

Now, BP = 10 - 5 = 5 cm

BP = BQ = 5 cm

Now,

BC = BQ + CQ

= 5 +  3

= 8 cm