F4 Circles (8): Tangent and radius

In the figure, PTQ is tangent to the circle at T.

x = (no need to input unit in your answer)

In the figure, PTQ is tangent to the circle at T.

y = (no need to input unit in your answer)

In the figure, TA and TB are tangents to the circle at A and B respectively. $\angle AOB=$  

•  $54\degree$  .

•  $63\degree$  .

•  $108\degree$  .

•  $252\degree$  .

In the figure, TA and TB are tangents to the circle at A and B respectively.  It is known now $\angle AOB=108\degree$  .  Then,  $\angle ATB=$  (no need to input unit in your answer)

In the figure, CB is tangent to the circle at B. AB is a diameter of the circle and ADC is a straight line. Name ONE triangle similar to $\Delta ABC$  (Please follow the corresponding vertices).