Given:
CP = 11 cm
BC = 7 cm
Property: If two tangents are drawn to a circle from one external point, then their tangent segments (lines joining the external point and the points of tangency on circle) are equal.
Using the above property,
CP = CQ = 11 cm (tangent from C)
BQ = BR (tangent from B)
And,
AP = AR (tangent from A)
Now,
BR = BQ = CQ – CB
= 11 cm – 7 cm
= 4 cm
Hence, BR = 4 cm