How to calculate the sine value of the included angle between straight lines on different planes?

The sine value formula of the angle between a straight line and a plane is: sin? +cos？ = 1。 The sine value of the line-plane angle is the absolute value of the cosine value of the normal vector angle between the line and the plane. Sine value is the value that the length of the opposite side in a right triangle is greater than the length of the hypotenuse. The sine value of any acute angle is equal to the cosine value of other angles, and the cosine value of any acute angle is equal to the sine value of other angles. Sinθ can also be understood as the ratio of the area of a unit isosceles triangle with the vertex angle θ to the area of a unit isosceles right triangle.

Solution of included angle of straight line in different planes;

1. Translate to find the angles formed by straight lines on different planes.

2. Prove that the angle or other angles are angles formed by straight lines in different planes.

3. Solve the triangle to find the size of the angle or the trigonometric function value of the angle.