Difference between revisions of "1979 USAMO Problems/Problem 2"
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<math>N</math> is the north pole. <math>A</math> and <math>B</math> are points on a great circle through <math>N</math> equidistant from <math>N</math>. <math>C</math> is a point on the equator. Show that the great circle through <math>C</math> and <math>N</math> bisects the angle <math>ACB</math> in the spherical triangle <math>ABC</math> (a spherical triangle has great circle arcs as sides). | <math>N</math> is the north pole. <math>A</math> and <math>B</math> are points on a great circle through <math>N</math> equidistant from <math>N</math>. <math>C</math> is a point on the equator. Show that the great circle through <math>C</math> and <math>N</math> bisects the angle <math>ACB</math> in the spherical triangle <math>ABC</math> (a spherical triangle has great circle arcs as sides). | ||
| + | |||
| + | ==Hint== | ||
| + | Draw a large diagram. A nice, large, and precise diagram. Note that drawing a sphere entails drawing a circle and then a dashed circle (preferably of a different color) perpendicular (in the plane) to the original circle. | ||
==Solution== | ==Solution== | ||
{{solution}} | {{solution}} | ||
| − | ==See | + | ==See Also== |
{{USAMO box|year=1979|num-b=1|num-a=3}} | {{USAMO box|year=1979|num-b=1|num-a=3}} | ||
| + | {{MAA Notice}} | ||
| + | |||
| + | [[Category:Olympiad Geometry Problems]] | ||
| + | [[Category:3D Geometry Problems]] | ||
Revision as of 10:58, 31 July 2020
Contents
Problem
is the north pole. 
and 
are points on a great circle through equidistant from . 
is a point on the equator. Show that the great circle through and bisects the angle 
in the spherical triangle 
(a spherical triangle has great circle arcs as sides).
Hint
Draw a large diagram. A nice, large, and precise diagram. Note that drawing a sphere entails drawing a circle and then a dashed circle (preferably of a different color) perpendicular (in the plane) to the original circle.
Solution
This problem needs a solution. If you have a solution for it, please help us out by adding it.
See Also
| 1979 USAMO (Problems • Resources) | ||
| Preceded by Problem 1 |
Followed by Problem 3 | |
| 1 • 2 • 3 • 4 • 5 | ||
| All USAMO Problems and Solutions | ||
The problems on this page are copyrighted by the Mathematical Association of America's American Mathematics Competitions. 
