1. Given a digits {} . Find the number of numbers of 6 digits which cantain or 's digit and they is permulated (For example 137456 and 314756 is one numbers).
3. Given is not isosceles triangle. and its incenter and circumcenter. The incircle tangents to at a point . The circumcircle of intersects at . Prove that , where is radius of incircle of .
5. Given points and lie a circle. . and incenters of . midpoints of arcs . Then prove that are concurrent.
Πηγή: artofproblemsolving
Πηγή: artofproblemsolving
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