Find cos(1680°) and sin(1680°). identify the measure of the reference angle.

Reference angle will be

Step-by-step explanation:

We have given

It can be written as

As 240° is lie in the third quadrant

And we know that for third quadrant

Reference angle is given by

So reference angle will be

Now

9.55 degrees.

step-by-step explanation:

the given angle is

1 cycle is equal to 2π radians. so 4π will be equal to two cycles.

5.166667π-4π = 1.166667π

hence, this angle goes a little more than negative x axis.

1.166667π-π= 0.166667π

hence, the reference angle is 0.166667π radians.

1 radian = 57.2958 degrees

now, in degrees, this should be equals to 9.55 degrees.