Question 1075418
Sin -5pi/12=sin of 19 pi/12 as well.
This is sin (10pi/12+9pi/12)
=sin(10pi/12)*cos(9pi/12)+cos(10pi/12)*sin(9pi/12)
both of these are negative
.5*(-sqrt(2)/2)+(-sqrt(3)/2*sqrt(2)/2)=
sqrt(2)/4+sqrt(6)/4
(1/4)(sqrt(2)+sqrt(6))
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This is sin (2A)=1/2
I know that pi/6 radians gives a sin of 1/2
Therefore, A must be pi/12 radians.
One can check by sin 2A=2sin A cos A =1/2
sinA cos A=1/4
If one uses pi/6 for A or 15 degrees, this will work.
Answer is pi/6 radians.