MathDB

angle between 2 planes, cube (2018 Adygea Teachers' Geometry Olympiad p4)

Source:

June 22, 2020

geometry3D geometrycubeangleplanes

Problem Statement

Given a cube

ABCDA_1B_1C_1D_1

with edge

5

. On the edge

BB_1

of the cube , point

K

such thath

BK=4

. a) Construct a cube section with the plane

a

passing through the points

K

and

C_1

parallel to the diagonal

BD_1

. b) Find the angle between the plane

a

and the plane

BB_1C_1