![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
![Review of performance metrics of spin qubits in gated semiconducting nanostructures | Nature Reviews Physics Review of performance metrics of spin qubits in gated semiconducting nanostructures | Nature Reviews Physics](https://media.springernature.com/full/springer-static/image/art%3A10.1038%2Fs42254-022-00484-w/MediaObjects/42254_2022_484_Fig1_HTML.png)
Review of performance metrics of spin qubits in gated semiconducting nanostructures | Nature Reviews Physics
![Predictive assembling model reveals the self-adaptive elastic properties of lamellipodial actin networks for cell migration | Communications Biology Predictive assembling model reveals the self-adaptive elastic properties of lamellipodial actin networks for cell migration | Communications Biology](https://media.springernature.com/full/springer-static/image/art%3A10.1038%2Fs42003-020-01335-z/MediaObjects/42003_2020_1335_Fig1_HTML.png)
Predictive assembling model reveals the self-adaptive elastic properties of lamellipodial actin networks for cell migration | Communications Biology
![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/NQgUg.png)