If If sin Θ = 21/29, then the y-component should be equal to 21 and the hypotenuse is equal to 29. In this case, using the pythgorean theorem, the x-component is obtained from (29^2-21^2)^1/2 equal to 20. Hence cos Θ should be +/-20/29. This has +/- because positive sine can be in quadrant II where cosine value is negative
