## En one year ago prove the formula: arccos x=1/2pi- arcsin x

1. anonymous

x should be a ratio, not an angle

2. anonymous

|dw:1441473183256:dw|

3. anonymous

arccos(x) = $$\theta$$

4. anonymous

arcsin(x) = $$\frac{\pi}{2}-\theta$$ => $$\theta = \frac{\pi}{2}-\arcsin\left(x\right)$$ => $$\arccos\left(x\right) = \frac{\pi}{2}-\arcsin\left(x\right)$$