In a circle, O is the center and AB is any chord and P is the point on the major segment with respect to the chord AB. If angle APB = 60o then find the value of angle OAB.
$25^o$
$30^o$
$40^o$
$45^o$
Solution
Angle APB = 60o then
Angle AOB $=120^0$
and angle OAB = angle OBA
Angle AOB + angle OAB + angle OBA =^ 180^o^
$2\times n + 120 = 180$
n = 30
Angle $OAB = 30^o$