posted by Lilly .
given that 0 is less then or equal to theta and theta is less then or equal to pi. ans cos theta = 2/squar root of 7. Find sin theta
cosθ = 2/√7 and 0 <= θ <= π means we are in the 1st quadrant.
so, sinθ = √(7-4)/√7 = √(3/7)