證明?$: (1) $?∵ 四邊形?$ A B C D $?是菱形?$, ∠A B C=60° ,$?
∴?$A B=B C=A D=C D, ∠A D C=∠A B C=60° \text {, }$?
∴?$\triangle {ADC} $?是等邊三角形,
∴?$A D=A C=A B=B C$?
∴?$\triangle A C B $?是等邊三角形,
∴?$∠{ACB}=∠{ACD}=60°, $?
∴?$∠{ACF}=120°, $?
∵?$∠{ADC}=∠{EDF}=60°, $?
∴?$∠{ADE}=∠{CDF}, $?
∵?$∠{EDF}+∠{ECF}+∠{DEC}+∠{DFC}=360°, $?
∴?$∠{DEC}+∠{DFC}=180°, $?
∵?$∠{DEC}+∠{AED}=180°, $?
∴?$∠{AED}=∠{DFC},$?
在?$ \triangle {ADE} $?和?$ \triangle {CDF} $?中,
?$\begin {cases}{∠A D E=∠C D F }\\{∠A E D=∠C F D }\\{A D=C D}\end {cases}$?
∴?$\triangle {ADE} \cong \triangle {CDF}({AAS}), $?
∴?${AE}={CF} ;$?
?$(2)$?過(guò)點(diǎn)?$B$?作?$ B H / / A C , $?交?$ A G $?的延長(zhǎng)線于點(diǎn)?$ {H} ,$?
∵?${BH}\ \mathrm {/} / {AC} ,$?
∴?$∠{H}=∠{GAE}, ∠{ABH}+∠{BAC}=180°, $?
∴?$∠{ABH}=120°=∠{ACF},$?
∵ 點(diǎn)?$ {G} $?為?$ {BE} $?的中點(diǎn),
∴?$B G=G E \text {, }$?
在?$ \triangle {AGE} $?和?$ \triangle {HGB} $?中,
?$\begin {cases}{∠H=∠G A E }\\{∠B G H=∠A G E, }\\{B G=G E}\end {cases}$?
∴?$\triangle {AGE} \cong \triangle {HGB}({AAS}) ,$?
∴?$A E=B H=C F, \quad A G=G H=\frac{1}{2} A H \text {, }$?
在?$ \triangle {ABH} $?和?$ \triangle {ACF} $?中,
?$\begin {cases}{A B=A C }\\{∠A B H=∠A C F, }\\{B H=C F}\end {cases}$?
∴?$\triangle {ABH} \cong \triangle {ACF}({SAS}), $?
∴?${AF}={AH}, $?
∴?${AF}=2 {AG} .$?