a) Ta có:
- Góc A = góc C = 90 độ (do tam giác ABC vuông tại A)
- Góc AHC = góc ABC (cùng chắn ở cung cấp)
=> Tam giác AHC đồng dạng với tam giác BAC theo góc.
b) Ta có:
- ab^2 = ah^2 + bh^2
- bc^2 = ch^2 + bh^2
=> ab^2 = ah^2 + bc^2 - ch^2
=> ab^2 = ah^2 + bc^2 - (ac^2 - ah^2)
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 + bc^2 - ac^2
=> ab^2 = 2ah^2 +