Mathematics for IGCSE & O level - Pythagoras' Theorem And Trigonometry (Section 7 - No. 40)
What is needed in order to use inverse trig functions on a calculator?
A known ratio.
Knowledge of the formula
Calculator must be in degree or radian mode
A labeled diagram.
Forklaring
In order to solve and use trig functions, ratios must be known. The mode of the calculator must also be set correctly.