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# In the circle above with center O, what is the measure of angle AOB?

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Re: In the circle above with center O, what is the measure of angle AOB? [#permalink]
Hey GMATInsight

Here sum of angle ABO & OBC would be 90 and not 180
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In the circle above with center O, what is the measure of angle AOB? [#permalink]
(1) The length of the arc AB is = $$Arc Length=π =(Angle of the arc/360°)*Circumference$$-> radius is unknown

(2) The measure of angle ABO is equal to the measure of angle OBC.
In triangle ABO and OBC we have
a) OB is part of both the triangle = common side
c) From Statement 2 angle ABO =Angle OBC = angle congruent
SAS triangles are congruent

AC = diameter... If a triangle is inscribed in a circle and has the diameter of the circle as the triangle’s hypotenuse, then that triangle is a right triangle.

so 2*angle ABO=90 ->angle ABO = 45
Angle BAO = Angle ABO = 45
Angle AOB = 90
So B

do correct me if i am wrong. thanks in advance
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Re: In the circle above with center O, what is the measure of angle AOB? [#permalink]
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Re: In the circle above with center O, what is the measure of angle AOB? [#permalink]
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