![geometry - How can I calculate $\alpha=\arccos\left(-\frac{1}{4}\right)$ without using a calculator? - Mathematics Stack Exchange geometry - How can I calculate $\alpha=\arccos\left(-\frac{1}{4}\right)$ without using a calculator? - Mathematics Stack Exchange](https://i.stack.imgur.com/O23Ia.png)
geometry - How can I calculate $\alpha=\arccos\left(-\frac{1}{4}\right)$ without using a calculator? - Mathematics Stack Exchange
![Casio Fx-85sp X Ii-scientific Calculator, Spanish And Portuguese, 293 Functions, Solar, Blue - Calculators - AliExpress Casio Fx-85sp X Ii-scientific Calculator, Spanish And Portuguese, 293 Functions, Solar, Blue - Calculators - AliExpress](https://ae01.alicdn.com/kf/Ub672568b044d4c6397b64efd0e555340g/Casio-FX-85SP-X-II-scientific-calculator-Spanish-and-Portuguese-293-functions-solar-Blue.jpg)
Casio Fx-85sp X Ii-scientific Calculator, Spanish And Portuguese, 293 Functions, Solar, Blue - Calculators - AliExpress
![Casio - fx-85SP X II Iberia - - Scientific calculator - Casio fx85SP X II Iberia - Casio.ledudu.com - Casio pocket computer, calculator, game and watch library. - RETRO CALCULATOR FX PB Casio - fx-85SP X II Iberia - - Scientific calculator - Casio fx85SP X II Iberia - Casio.ledudu.com - Casio pocket computer, calculator, game and watch library. - RETRO CALCULATOR FX PB](https://casio.ledudu.com/images/calculs/casio/machines/fx85SPXIIIberia.jpg)
Casio - fx-85SP X II Iberia - - Scientific calculator - Casio fx85SP X II Iberia - Casio.ledudu.com - Casio pocket computer, calculator, game and watch library. - RETRO CALCULATOR FX PB
![Casio Fx-92 *like new*, Hobbies & Toys, Stationery & Craft, Stationery & School Supplies on Carousell Casio Fx-92 *like new*, Hobbies & Toys, Stationery & Craft, Stationery & School Supplies on Carousell](https://media.karousell.com/media/photos/products/2021/7/5/casio_fx92_like_new_1625473180_a9b31794.jpg)
Casio Fx-92 *like new*, Hobbies & Toys, Stationery & Craft, Stationery & School Supplies on Carousell
Wie kann man mit dem Rechner Casio fx-87de plus arcsin , arccos , arctan , arccot eingeben? | Mathelounge
![Why is the TI 89 evaluating arcTan incorrectly?(how can I get the answer in degrees) : r/calculators Why is the TI 89 evaluating arcTan incorrectly?(how can I get the answer in degrees) : r/calculators](https://preview.redd.it/ly1t3rtbjg141.jpg?auto=webp&s=7480fd2c1cd7b439c31c0880e9387bb77bd23061)