Traditional Culture Encyclopedia - Photography and portraiture - In the S-ABCD of a regular pyramid, O is the photography of the vertex on the bottom, P is the midpoint of the side SD, SO=OD, then the straight line BC and the plane P ..

In the S-ABCD of a regular pyramid, O is the photography of the vertex on the bottom, P is the midpoint of the side SD, SO=OD, then the straight line BC and the plane P ..

The wrong topic is because of projection, not photography. Cheated me of my photography career. Junior high school topic, hehe ... angle SOD = 90 degrees, so=od, then sd=√2so=cd, so the sides are equilateral triangles, then ap is perpendicular to sd and CP is perpendicular to sd, that is, sd is perpendicular to plane pac, which proves that ad is parallel to bc, that is, angle sap is equal to the included angle between bc and plane pac, that is, 30 degrees.