Subcontests
(5)ratio of triangle areas equal to ratio of chords, intersecting circles related
Given are two points B,C. Consider point A not lying on the line BC and draw the circles C1(K1,R1) (with center K1 and radius R1) and C2(K2,R2) with chord AB,AC respectively such that their centers lie on the interior of the triangle ABC and also R1⋅AC=R2⋅AB. Let T be the intersection point of the two circles, different from A, and M be a random pointof line AT, prove that TC⋅S(MBT)=TB⋅S(MCT) no of subsets of {1,2,3,...,2003} with even number of elements
Consider the set M={1,2,3,...,2003}. How many subsets of M with even number of elements exist?