OK, by now you may be thinking, “That’s cool, but why bother with a new system of angle measure?” Here are a few reasons why radians are easier…
Do you remember how sine and cosine are defined?
With angles expressed in radians, we have this tidy system, all based on the same “pure” numbers.
The graphs look like this, the parent function, with equal units in x and y.
And not this, which is actually a horizontal stretch.