# What is the length of the radius of the circle

**Geometry**Level pending

ABCD is a cyclic quadrilateral.

AB = 9 cm BC = 7 cm CD = 6 cm AD = 2 cm

Find the length of the radius of the circumcircle of this quadrilateral in centimetres.

Type in the square of the length of the radius into the answer box as a decimal fraction.

If there is not enough information given in the diagram to find the length of the radius, type in -1 as the answer.