ABCD is a cyclic quadrilateral. The tangents to the circle at the points A and C on it, intersect at P. If $$\angle ABC = 98^\circ$$, then what is the measure of $$\angle APC$$?
ACD is a cyclic quadrilateral so,
$$\angle ABC +Â \angle ADC = 180\degree$$
$$\angle ADC = 180 - 98 = 82\degree$$
$$\angle AOC = 2 \times \angle ADC = 2 \times 82 = 164\degree$$
In quadrilateral AOCP-
$$\angle OAP +Â \angle APC +Â \angle PCO +Â \angle COA = 360\degree$$
$$\angle OAP =Â \angle PCO = 90\degree$$
($$\because$$ tangent angle)
$$\angle APC = 360 - 90 - 90 - 164 = 16\degree$$
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