106@ is in [3pi/2,2pi]
So, @/2 is in [3pi/4,pi] i.e. in second quad. (cos is negative while sin is positive)
cos(@) = 3/7 = 2cos2(@/2)-1
=> cos2(@/2) = 10/14
=> cos(@/2) = -√5/7
sin(@/2) = 1-cos2(@/2) = √2/7
if α lies in the fourth quadrant and cosα=3/7 find the values of sinα/2 and cosα/2 ?
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1 Answers
106