Question

o is the centre of the circle Angle AOB=60° Then Angle ACB? ADB?

Answer 1

60 degree - 180degree = 20degree

Answer 2

Use Half Angle Theorem

Step-by-step explanation:

$\angle$ AOB + $\angle$AOC = 180 (sum of all angle in a straight line is 180)

$\angle$ AOC = 180–60

$\angle$AOC = 120 °

In this question $\angle$BAC= 90 degree because the angle in circumference of half circle should be 90 degree.

Sides AO,OB&OC are equal because these are the radius of circle.

$\angle$ OAB & $\angle$OBA are equal (OB=OA), now in triangle AOB

let $\angle$ ABO = x = $\angle$ ABC,

$\angle$ ABO = $\angle$BAO

x+x+$\angle$ AOB=180 (sum all angle in triangle is 180)

2x = 180–60

x = 60 degree = $\angle$ ABC

$\angle$ BAC = 90°

$\angle$ACB = 30° (Angle = $\frac {1}{2} (\angle AOB),$ by Half angle theorem)