Question

In the figure alongside AB is the diameter of the circle, having point D on circumferenc find m(arc DB) if ZABD = 77°

A- 26°
B- 13°
C- 39°
D - 42°​

Answer 1

ZACB=90° (Angle subtended on semi circle)

In, AACB,

ZCAB=180°-(ZACB+ZCBA)

=180˚-(90° +70°)

=20°

Now,

ZDCA+ZACB+/BAC+/DAC=180° [Sum

of opp. anglesof cyclic quadrilateralis supplementary.] ZACD=180°-40°

ZDCA+90° +20° +30° =180°

ZACD=40°

Hence, 40˚ is the correct answer.