1. arcsin sqrt2/2
= pi/4
2. arcsin sqrt3/2
= pi/3
3. cos^-1 sqrt2/2
4. arcsin 0.3907
= 0.401
5. arccos 0.7990
= 0.645
6. tan^-1 0.3673
= 0.352
you can use a calculator to check, you know
