Script Foxpro "Menghitung Luas Segitiga "

IF thisform.optiongroup1.option1.Value=1 then
   thisform.text3.Value=(0.5*(VAL(thisform.text1.Value)*VAL(thisform.text2.Value)))
   ELSE
IF thisform.optiongroup1.option2.Value=1 then
   thisform.text1.Value=(VAL(thisform.text3.Value)/(0.5*VAL(thisform.text2.Value)))
   ELSE
IF thisform.optiongroup1.option3.Value=1 then
   thisform.text2.Value=(VAL(thisform.text3.Value)/(0.5*VAL(thisform.text1.Value)))

ENDIF
ENDIF
ENDIF

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thisform.text1.Value=""
thisform.text2.Value=""
thisform.text3.Value=""