【Haichuan Teahouse】Brain-teasing Series: How to Draw This Auxiliary Line Properly
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As shown in square ABCD, the area of the square is 12. AE = DE, and EF = 2CF. What is the area of the shaded region in the figure? If you learn how to draw auxiliary lines, this problem isn’t difficult.
Draw a straight line through point F that is perpendicular to line AB; this line intersects line AB at point G and perpendicular to line DC at point H. First, calculate the length of FH. . . . . .
Draw a line from point F parallel to DC; the result is 5
This method is good; it’s simple and fast.
Well, calculate it proportionally. A line drawn from point F parallel to DC cuts the square, and the portion that is cut off is one-sixth of the square. The shadow is half of the large rectangle~