Question

How do you evaluate the sine, cosine, and tangent of the angle 225 degrees without using a calculator?

Answer 1

Find 3 trig functions of arc 225 deg
Answers: sin = cos = -(sqrt22)/2 , tan = 1

Explanation:

On the trig unit circle, the arc 225 is in Quadrant III.

`sin 225 = sin (45 + 180) = - sin 45 = -(sqrt2)/2`

`cos 225 = cos (45 + 180) = - cos 45 = - (sqrt2)/2`

tan 225 = sin/cos = 1