Find the value of sin(a/2) if cosa= 12/13

sin = ±

Step-by-step explanation:

We very well know that,

cos2A=1−2sin²A

⟹ sinA = ±

As required,  set A =   &   cos a=      ,thus we get

sin =±  

∴ sin =± = ±

   since ,360° < <450°

             ,180° < <225°

Now, we are to select the value with the correct sign. It's is obvious from the above constraints that the angle a/2 lies in the III-quadrant where 'sine' has negative value, thus the required value is negative.

hope it helped!

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step-by-step explanation: