**Question:**

Quadrilateral ABCD is circumscribed to a circle. If AB = 6 cm, BC = 7 cm and CD = 4 cm, then the length of AD is

(a) 3 cm

(b) 4 cm

(c) 6 cm

(d) 7 cm

**Solution:**

We know that when a quadrilateral circumscribes a circle then sum of opposites sides is equal to the sum of other opposite sides.

∴ AB + DC = AD + BC

⇒6 + 4 = AD + 7

⇒ AD = 3 cm

Hence, the correct answer is option (a).