Question

Find the value of the unknown in the following figures.

Answer 1

In the given figure, AC is a tangent to the circle & O is the centre of the circle.

$\angle$CBO = ${90}^0$ (Line from the centre to the tangent of the circle is always perpendicular)

$\angle$ABO = ${90}^0$ (Line from the centre to the tangent of the circle is always perpendicular)

Now, In $\Delta$CBO, $\angle$COB = $({180}^0–{90}^0-{15}^0)$ = ${75}^0$

Now, In $\Delta$AOB, $\angle$AOB = $({180}^0–{90}^0-{40}^0)$ = ${50}^0$