Inverse Trigonometric Functions Arcsin and Arccos

Notions of inverse sine and inverse cosine have been introduced. Their basic properties have been proved. In this paper r, s are real numbers and i is an integer number. We now state two propositions: (1) If 0 ≤ r and r < s, then ⌊ r s ⌋ = 0. (2) For every function f and for all sets X, Y such that f ↾X is one-to-one and Y ⊆ X holds f ↾Y is one-to-one. 2. Functions sine and cosine We now state four propositions: (3) −1 ≤ sin r. (4) sin r ≤ 1.