如图,P为正方形ABCD内一点,若PA:PB:PC=1:2:3,求∠APB

2025-05-20 03:14:55
推荐回答(1个)
回答1:

解:把△BAP绕点B旋转90°到△BCP‘,(如图)
则:∠PBP‘
=
90°
BP’
=
BP
P‘C
=
AP

∠PP’B
=
45°
根据题意可设:AP
=
a
BP
=
2a
PC
=
3a
则:
PP'
²= 2*BP²
=
8

P‘C²
=
1
PC²
=
9

PC²
=
PP’²+P‘C²
∴∠PP’C
=
90°

故:∠APB=∠BP‘C
=
135°。