Mathematics for IGCSE & O level - Pythagoras' Theorem And Trigonometry (Section 1 - No. 42)
Which formula helps to determine the angle in a triangle if we know the area and the lengths of two sides?
Area = 1/2*ab*sinC, rearrange for angle
Pythagoras' theorem
Cosine rule
sinA/a = sinB/b
Explication
Area = 1/2 * ab * sinC, where C can be found knowing the area and sides a,b.