毕达哥拉斯定律 口直角三角 Proof: Construct F so that CF is perpendicular to AB. 形三边a、 c2 b、c,c cl 为斜边， E 则：a2+ b2=c2 b a*a/2= a B area DBC area DBA (by shearing) area CBE (by side-angle-side) area FBE(by shearing) a a =cl*c/2 Similarly: b*b/2=c2*c/2 D Add and then multiply by 2 to get: a*a+b*b=(c1+c2)*c=c*c毕达哥拉斯定律 o直角三角 形三边a、 b、c，c 为斜边， 则：a2 + b2 = c2