高階math-u07-d04
The angle between a straight line and a plane equals:
A. 90 degrees minus the angle between the line and the normal to the plane✓ 答案
B. The angle between the line and the normal to the plane
C. Always 45 degrees
D. The angle between the line and any plane through it
解說
The line-normal angle and the line-plane angle are complementary, so the line-plane angle is 90 degrees minus the line-normal angle.