Question

9. AB is diameter of circle
whose centre is O. Cand D are
the points on circle such that
ABCD is cyclic quadrilateral. If
ZADC = 120°, then find ZBAC
*​

Answer 1

Answer:

Construction: Join B and D. This forms a right triangle ADB.

From the figure, we can say that angle B is 50 deg  [opposite angles in a cyclic quadrilateral are supplementary]

Consider triangle ACB.

Angle ACB is 90 deg   [ angle in a semicircle is 90 deg]

Angle ABC is 50 deg  

So, angle BAC is 40 deg   [angle sum property of a triangle].

Angle BAC is 40 deg.