Procedure :
(i) Draw a circle of many radius with centre O.
(ii) Mark any four points A,B,C and D on the boundary. Make a cyclic quadrilateral ABCD and name the angles as in Fig. 1
(iii) Make a replica of the cyclic quadrilateral ABCD with the help of tracing paper
(iv) Make the cutout of the angles A,B,C and D as in Fig. 2
(v) Paste the angle cutout `angle1,angle2,angle3` and `angle4` adjacent to the angles opposite to A,B,C and D as in Fig . 3
Measure the angles `angle1+angle3`, and `angle2+angle4`.

Observe the Fig. 3 and complete the following :
`{:((i),angleA+angleC= . . . . . . . ,(ii),angleB+angleD =. . . . . . .),((iii),angleC+angleA= . . . . . . .,(iv),angleD+angleB= . . . . . . .):}`
2. Sum of opposite angles of a cyclic quadrilateral is . . . . . . . .
3. The opposite angles of a cyclic quadrilateral is . . . . . . .