What are radians? Why use them? Converting between degrees and radians.
The basic trig functions using radians.
Solving 1 stem trig equations using radians - using features of the graph and using the unit circle method.

Angles can be
measured in Degrees or Radians.
One Radian is 180/π
degrees, or about 57.296°

A Radians is: the angle made by taking the radius and
wrapping it along the edge of the circle:

So,
a Radian "cuts out" a length of a
circle's circumference equal to the radius.

There are 2π
radians in a full circle

In other words,
if you cut up pieces of string exactly the
length from the center of a circle to its edge,
how many pieces would you need to go around the
edge of the circle?

Answer:
2π, or about 6.28
pieces of string.

Radians Preferred by Mathematicians

Because the radian is based on the
pure idea of "the radius being laid along the
circumference", it gives simple and natural results
to many angle-related mathematics.

So, degrees are easier to use in everyday work, but
radians are much better for mathematics