In the discussion on vector decomposition and trigonometry in tension force analysis, participants clarify the roles of sine and cosine in relation to angles in right triangles. Sine is associated with the vertical component, while cosine corresponds to the horizontal component, based on trigonometric principles. The importance of understanding vector decomposition is emphasized, particularly in analyzing forces. Participants suggest drawing a labeled right triangle to visualize the tension force and its components. Overall, the conversation focuses on applying trigonometric functions to resolve forces in physics problems.