A,B,C,D are four points on a circle with radius R such that ACis perpendicularto BD and meets BD at E. prove that:EA2+EB2+EC2+ED2=4R2

you say A,B,C,D are 4 points on cirrcle with radius R and AC perpendicular to BD from these we say AC and BD are meets at center of the circle.so EA=EB=EC=ED=R that's mean EA2+EB2+EC2+ED2=4R2