One chord of a circle is known to be 10 cm. The radius of this circle must be

ABCD is a cyclic quadrilateral such that ∠ADB =30° and ∠DCA =80°, then ∠DAB =

A chord of length 14 cm is at a distance of 6 cm from the centre of a circle. The length of another chord at a distance of 2 cm from the centre of the circle is

ABC is a triangle with B as right angle, AC=5 cm and AB = 4 cm. A circle is drawn with A as centre and AC as radius. The length of the chord of this circle passing through C and B is

If AB, BC and CD are equal chords of a circle with O as a centre and AD diameter, than ∠AOB =