Answer:
cos theta =± 2/3
Explanation:
sin theta = sqrt(5) /3
sin theta = opp side / hypotenuse
We know that
a^2 + b^2 = c^2 from the pythagorean theorem
opposite side ^2 + adjacent side ^2 = hypotenuse ^2
( sqrt(5)) ^2 + adjacent side ^2 = 3^2
5 + adjacent side ^2 = 9
Subtract 5 from each side
5-5 + adjacent side ^2 = 9-5
adjacent side ^2 = 4
Taking the square root of each side
adjacent side = ±2
We know that
cos theta = adj side / hyp
cos theta =± 2/3