Let a be the second quadrant angle, Sina = 1 / 2; find the value of sin (a + Wu / 4) / sin2a + cos2a + 1

Let a be the second quadrant angle, Sina = 1 / 2; find the value of sin (a + Wu / 4) / sin2a + cos2a + 1

A is the second quadrant angle, Sina = 1 / 2 cosa = - √ 3 / 2Sin (a + Wu / 4) / sin2a + cos2a + 1 = (sinacos π / 4 + cosasin π / 4) / (2sinacosa + 2cos ^ 2a) = √ 2 / 2 (sinacosa) / 2cosa (Sina + COSA) = (√ 2 / 2) / 2cosa = (√ 2 / 2) / (- √ 3) = - √ 6 / 6

If cosa = 2 / 3 and a is the fourth quadrant angle, then Sina sinacosa =?

Cosa = 2 / 3 and a is the fourth quadrant angle
So Sina = - √ 5 / 3
sina-sinacosa
= -√5/3 + √5/3 × 2/3
= -√5/9
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