Chapter 1.7, Problem 31ES

Most scientific calculators have keys for the values of only ${\sin }^{-1}x,{\cos }^{-1}x,$ and ${\tan }^{-1}x$ . The formulas in Exercise 30 show how a calculator can be used to obtain values of ${\cot }^{-1}x,{\sec }^{-1}x$ , and ${\csc }^{-1}x$ for positive values of $x$ . Use these formulas and a calculator to find numerical functions. Express your answers in degrees, rounded to the nearest tenth of a degree.

(a) ${\cot }^{-1}0.7$

(b) ${\sec }^{-1}1.2$

(c) ${\csc }^{-1}2.3$