موضوع خاص باسئلة واستفسارات الطلاب (ليلة امتحان الجبر والفراغية )

[salahragabaly]

we know that dihedral angle is the angle between two intersection planes and included between two st. lines each one contain in one plane of them are perpendicular to intersection st. line of two planes and intersect on point on that intersection st. line where the plane whhch formed from that two st. line is calld the plane angle of a dihedral angle
therfor the correct answer the plane angle of a dihedral angle is the angle formed by the line of intersiction of the two planes with a plane perpendicular to its edge