Trigonometric ratios of an acute angle of a right-angled triangle. Proof of their existence (well defined); motivate the ratios, whichever are defined at 0° and 90°. Values (with proofs) of the trigonometric ratios of 30°, 45° and 60°. Relationships between the ratios.
10.T.IT.2
Trigonometric Identities: Proof and applications of the identity sin^2 A + cos^2 A = 1. Only simple identities to be given. Trigonometric ratios of complementary angles.