Sin cos tan values are the primary functions in trigonometry. Learn the values for all the angles, along with formulas and table. Also, learn to find the values for these trigonometric ratios.
We can give the proof of sin A + sin B formula (sin A + sin B = 2 sin ½ (A + B) cos ½ (A - B)) using the expansion of sin(A + B) and sin(A - B) formula. We know, using trigonometric identities, ½ [sin(α + β) + sin(α - β)] = sin α cos β, ...