Answer:
<h3>

=

</h3>
Step-by-step explanation:
Given AB is a tangent to the circle O and touch the circle at point A.
We know that tangent is a line which touches the circle only at one point .

We know that the radius of circle is perpendicular to the tangent.
In the figure OA is radius of given circle
AB is a tangent line
Radius OA is perpendicular to the tangent AB.
Therefore,
We know that sum of angles of a triangle is
.
By sum of angle of triangle property
Therefore,in triangle OAB
OAB+
ABO+
AOB=
By angle sum of triangle property
90+55+

<h3>

</h3><h3>Hence, the angle ABO=

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