SOLUTION: If 0 < A < pi/2 and {{{ sinA+1=2* sqrt( 1-sin^2(A) ) }}}, determine the value of sinA.

Let  t = sin(A).  Then


t + 1 = .


Square both sides:


t^2 + 2t + 1 = 4*(1-t^2)


t^2 + 2t + 1 = 4 - 4t^2


5t^2 + 2t - 3 = 0


 =  =  = 


 =  =  =  = 0.6.


 =  = -1.


Since the angle A is in QI, the only value for sin(A) is 0.6.


Answer.  At given conditions, sin(A) = 0.6.