Question

Evaluate: sin (225degree)

Answer 1

Sin(225)

225 degrees is in the 3rd quadrant.  And in the third quadrant only tangent is positive,  sin is negative.

For third quadrant, basic angle = 225 - 180 = 45

sin225 = - sin45

sin225 = - sin45 = -0.7071

sin 225° ≈ -0.7071