The distance between the centres of two equal circles each of radius 4 cm is 17 cm. The length of a transverse tangent is:

15 cm

We know that,

(Length of transverse tangent)² = [(distance between the centres)² – (r₁ + r₂)²]

We have,

Radius of first circle = 4 cm

Radius of second circle = 4 cm

Distance between the centres of two circles = 17 cm

According to the formula = (PQ)² = (17)² – (4 + 4)²

= (PQ)² = 289 – 64

= (PQ)² = 225

= PQ = 15 cm