import sys
from PyQt5.QtWidgets import QApplication, QMainWindow
from PyQt5.QtWidgets import QLabel, QLineEdit, QPushButton


class MainWindow(QMainWindow):

    def __init__(self):
        super().__init__()

        baseLabel = QLabel(self)
        baseLabel.setText('Alap')
        baseLabel.move(50, 30)
        self.baseEntry = QLineEdit(self)
        self.baseEntry.move(130, 30)

        heightLabel = QLabel(self)
        heightLabel.setText('Magasság')
        heightLabel.move(50, 70)
        self.heightEnty = QLineEdit(self)
        self.heightEnty.move(130, 70)

        calcButton = QPushButton(self)
        calcButton.setText('Számít')
        calcButton.move(90, 120)
        calcButton.clicked.connect(self.on_click_calcbutton)

        areaLabel = QLabel(self)
        areaLabel.setText('Terület')
        areaLabel.move(50, 160)

        self.areaEnty = QLineEdit(self)
        self.areaEnty.move(130, 160)

        self.setGeometry(100,100,320,200)
        self.setWindowTitle('Háromszög területe')
        self.show()

    def on_click_calcbutton(self):
        base = int(self.baseEntry.text())
        height = int(self.heightEnty.text())
        area = base * height / 2
        self.areaEnty.setText(str(area))
        self.baseEntry.setText('')
        self.heightEnty.setText('')

if __name__ == '__main__':
    app = QApplication(sys.argv)
    mainWindow = MainWindow()
    sys.exit(app.exec_())