It is known that a is the third quadrant angle, and COS (A / 2) + sin (A / 2) = - (√ 6) / 3, √ (1 + COSA) = - {2Sin (A / 2) 1 ask me to calculate the value of COS (A / 2) - sin (A / 2) 2 question: （cos(a/2)*cos(a+3.14/4))/(1+tan(a/2))

It is known that a is the third quadrant angle, and COS (A / 2) + sin (A / 2) = - (√ 6) / 3, √ (1 + COSA) = - {2Sin (A / 2) 1 ask me to calculate the value of COS (A / 2) - sin (A / 2) 2 question: （cos(a/2)*cos(a+3.14/4))/(1+tan(a/2))

Now that you calculate the value of COS (A / 2) - sin (A / 2), and COS (A / 2) + sin (A / 2) = - (√ 6) / 3, then the values of COS (A / 2) and sin (A / 2) will know the value of Tan (A / 2), that is, cos (a + 3.14 / 4) = √ 2 / 2 * (COSA Sina) reuse formula: cosa = [cos (A / 2)] ^ 2 - [sin (A / 2)] ^ 2sina = 2 * cos