What is Official Answer?
(1)(pls chk attachment for the drawings)
In the fig shown, point O is the centre of the semi-circle and points B, C and D lie on the semi-circle. If the length of line segment AB is equal to the length of line segment OC, what’s the degree measure of angle BAO?
(1)The degree measure of angle COD is 60 degree.
(2)The degree measure of angle BCO is 40 degree.
In the Fig shown, the measure of angle PRS is how many degrees greater than the measure of angle PQR?
(1)The measure of angle QPR is 30 degrees
(2) Sum of the measure of angles PQR and PRQ = 150 degrees
for more detail check theis link ....
http://www.urch.com/forums/showthread.php?t=36638&highlight=COD (HardBin GMATPrep - Yet Another set of circumscribed Triangles)
For the second one i think the answer should be D.
angle PQR = x
angle PRQ = y
for a) angle QPR = 30
that makes x + y = 150.
according to the exterior angle theorm we get
angle PRS = angle RPQ + angle PQR
= 30 + angle PQR
angle PRS - angle PQR = 30.
i think this is what is asked.
and also we can get the same result from b) option as well.
Correct me if i am wrong.
i think the answer for first one is b.
OB = OC ( radii of the same circle)
AB = OC ( given information)
so AB = OB
and so also angle BCO = angle OBC -------(1)
angle BCO = 40 ( according to condition B)
so angle OBC = 40
and angle OBC + angle OBA = 180
so angle OBA = 140
angle OBA + angle BAO + angle OAB = 180
140 + angle OAB + angle OAB = 180------- as from (1) above
so angle OAB = 20.
so i think the answer should be B.
Let me know if i am wrong somewhere.
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