Angle between Two Planes 面面角

作者:
Alex CHIK
Given that angle BAC is 40 degrees. Where should be points B and C such that the angle between the two planes is also 40 degrees? 已知角BAC固定為40度。移動B點和C點到甚麼位置,兩平面的交角才是40度?
GeoGebra 互動數學教室 http://www.geogebra.hk