This is circle based question from Chapter name- circles

Topic – Angle properties of circles

Chapter number- 15

In this question we have figure of circles with constructions and we have to find the value of x using basic properties of circles.

ICSE Avichal publication

Understanding ICSE Mathematics

Question no2

Solution:(i) ∠ACB = ∠ADB

(Angles in the same segment of a circle)

But ∠ADB = x°

∠ABC = x

^{o}Now in ∆ABC

∠CAB + ∠ABC + ∠ACB = 180

^{o}40

^{o }+ 90^{0 }+ x^{o }= 180^{o}(AC is the diameter)

130

^{o + }x^{o }= 180^{o}x

^{o }= 180^{0 }– 130^{o}= 50^{o}