Question

Answer 1

\(a,\)

Các HTL: 

\(FD^2=FH\cdot EF\\ ED^2=EH\cdot EF\\ DH^2=FH\cdot HE\\ \dfrac{1}{HD^2}=\dfrac{1}{FD^2}+\dfrac{1}{DE^2}\\ DH\cdot EF=DF\cdot DE\\ DF^2+DE^2=EF^2\)

Answer 2

\(b,\)

+)Hình 1: Áp dụng HTL:

\(AH^2=BH\cdot HC=36\\ \Rightarrow X=AH=6\left(đv\right)\)

+)Hình 2: Áp dụng HTL:

\(\left\{{}\begin{matrix}x^2=1\left(1+3\right)=4\\y^2=3\left(1+3\right)=12\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}x=2\left(đv\right)\\y=2\sqrt{3}\left(đv\right)\end{matrix}\right.\)

*đv là đơn vị(nếu có)