चक्रीय समलम्ब चतुर्भुज ABCD की भुजाये AB ।। DC तथा AB वृत्त का व्यास है। यदि `angleCAB=30^(@)` है, तब `angleADC` है

Options

A. `60^(@)`
B. `120^(@)`
C. `150^(@)`
D. `30^(@)`

Answer

B

Explanation

According to question,

Given, AB is a diameter
`angleCAB = 30^(@)`
As we know that
`angleACB = 90^(@)`
`therefore angleACB+angleCAB+angleCBA=180^(@)`
`angleCBA=180^(@)-90^(@)-30^(@)`
`angleCBA = 60^(@)`
Note: In a cyclic trapezium sum of opposite angle is `180^(@)` एक चक्रीय समलम्ब चतुर्भुज कोंडो का योग `180^(@)` होता हैं
`(therefore angleD+angleB=180^(@)`
`angleD=180^(@)-60^(@)`
`angleD=120^(@)`