Question

如图：在三角形ABC中，AB=AC，P为BC上任意一点。求证：AP平方=AB平方—PB乘PC

最好要过程哦

Answer 1

利用余弦定理AP�0�5=AB�0�5+BP�0�5-2*BP*AB*cos∠ABP，AB*cos∠ABP=1/2BC∴AP�0�5=AB�0�5+BP�0�5-2*BP*AB*cos∠ABP=AB�0�5+BP*(BP-BC)=AB�0�5-BP*CP