Sin A equals the opposite side divided by the hypotenuse. As A increases, towards 90 degrees, sin increases up to a value of 1. For example, sin 35 degrees is 0.57, sin 65 degrees is 0.90 and sin 89 degrees is 0.9998. The best way to visualize this is to draw these approximate angles on paper within the right triangle and see how the hypotenuse and opposite relative lengths change.
