MathDB

angle between planes, starting with an equilateral

Source: 2003 Romania District VIII P2

May 24, 2020

3D geometrygeometryanglesplanesEquilateral

Problem Statement

Let

ABC

be an equilateral triangle. On the plane

(ABC)

rise the perpendiculars

AA'

and

BB'

on the same side of the plane, so that

AA' = AB

and

BB' =\frac12 AB

. Determine the measure the angle between the planes

(ABC)

and

(A'B'C')