(X- 1)^

+

(y- 1)^

= 1

It can be seen that the center of the circle is on O'( 1, 1) and the radius is 1.

Draw a graph and make two tangents pass through point P (3 3,2).

The upper tangent is parallel to the X axis, and the length from point P to two tangent points is 2.

tan(a/2)= 1/2

cosa=[ 1-tan^(a/2)]/[ 1+tan^(a/2)]=[ 1-( 1/2)^]/[ 1+( 1/2)^]=3/5