Question

if cos theta =-2/3 then sin theta/2​

Answer 1

Step-by-step explanation:

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Answer 2

sin a= 2/3

We know that:

sin^2 a + cos^2 a= 1

==> cos^2 a = 1 - sin^2 a

==> cos^2 a = 1- (2/3)^2

==> cos^2 a = 1- 4/9

==> cos^2 a= 5/9

==> cos a = sqrt5/3

But a is in the 2nd quadrant where cos a ia negative:

==> cos a = - sqrt5/3

i think this will help you out