Question

Find cos(405°) and sin(405°). Identify the measure of the reference angle.

Answer 1

Answer:

Reference angle will be $45^{\circ}$

$cos(45^{\circ})=0.707$

$sin(45^{\circ})=0.707$

Step-by-step explanation:

We have given $cos(405^{\circ})$

Which can be written as $cos(405^{\circ})=cos(360+45)$

We know that $45^{\circ}$ is present in first quadrant

And in first quadrant the reference angle is angle itself

So reference angle will be = 45°

Now $cos(405)=cos(2\pi +45)=cos45^{\circ}=0.707$

And $sin(405)=sin(2\pi +45)=sin45^{\circ}=0.707$