Geometry Problem
Level: Mathematics Education, High School, Honors Geometry, College.
Click the figure below to see the problem 718 details.
Monday, January 23, 2012
Problem 718: Intersecting Circles, Midpoint, Angle, Measurement
Labels:
angle,
arc,
intersecting circles,
measurement,
midpoint
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Extend CDO' to cut the circle O' at E.
ReplyDeleteJoin AE, BE. Let angle AEB = y
By the result of Problem 717,
y = 65 deg
But AEBD is a cyclic quadrilateral.
So x + y = 180 deg
Hence x = 115 deg
By applying the formula that angle bda=90+bca/2 therefore half of 50=25 and by adding 90 we get 90+25=115
ReplyDeletetherefore measure of angle bda =115
x
ReplyDelete= angle subtended by major arc AB of circle(O')at D
= half the ∠ subtended by arc AB of circle (O')at center O'.
= (1/2)major∠AO'B
= (1/2)(360°-minor∠AO'B)
= (1/2)[360°-(180°-∠ACB)] (∵ AO'BC is a cyclic quadrilateral)
= (1/2)(180°+∠ACB)
= (1/2)(180°+50°)
= (1/2)(230°)
= 115°
<AO'B=180-50=130
ReplyDelete<ADB=180-<AO'B/2=180-65=115