How much is sin0!
0, you can draw a triangle, in the side ratio!
SIN0=0?cos0=1?
Is a directed line a vector
No, it's a quantity with both size and direction. It's a vector. There's a line segment with both length and direction, so it's an appropriate amount. But other things, such as acceleration, are also vectors
Who has the specific value of sin0-90 degrees?
a 0` 30` 45` 60` 90`
sina 0 1/2 √2/2 √3/2 1
cosa 1 √3/2 √2/2 1/2 0
tana 0 √3/3 1 √3 None
cota None √3 1 √3/3 0