Is it because we need to rotate the plane to have normal w to account for perpendicular L_i that we have cos\theta in the expression?

intelligentDungBeetle

since theta is a solid angle from 0 to 4pi, does taking the cosine work the same way as taking the cosine of an angle in a unit circle (in radians) ?

kye

@anonymous yes

@intelligentDungBeetle the normal and the incoming angle define a circle (a "slice" through the sphere) so it's taking the cosine of an angle on a circle as usual

Is it because we need to rotate the plane to have normal w to account for perpendicular L_i that we have cos\theta in the expression?

since theta is a solid angle from 0 to 4pi, does taking the cosine work the same way as taking the cosine of an angle in a unit circle (in radians) ?

@anonymous yes

@intelligentDungBeetle the normal and the incoming angle define a circle (a "slice" through the sphere) so it's taking the cosine of an angle on a circle as usual