In [math]\Delta ABC[/math], [math]D[/math], [math]E[/math] and [math]F[/math] are midpoints of sides [math]\bar{BC}[/math], [math]\bar{AC}[/math] and [math]\bar{AB}[/math] respectively. How to show [math]A(\Delta DEF)=\dfrac{1}{4}A(\Delta DEF)[/math]?
How do things sink in water?