This is the basic and conceptual question from Chapter name- circles

Topic – Angle properties of circles

Chapter number- 15

In the figure (i) ABCD is a quadrilateral inscribed in a circle with centre O. CD is produced to E. ∠ADE = 70° and ∠OBA = 45°, then we have to calculate (i) ∠OCA (ii) ∠BAC

In figure (ii) given below, ABF is a straight line and BE || DC.

∠DAB = 92° and ∠EBF = 20°, now we have to find : (i) ∠BCD (ii) ∠ADC.

ICSE Avichal publication

Understanding ICSE Mathematics

Question 9

Solution:(a) ABCD is a cyclic quadrilateral