# Math 22a Announcements

- Today Friday, David's proof seminar is at 12:30 and 3 both in SC 221.
Oliver has office hours from 11:30 to 12:30.
- In the distributed handout unit 7, a square was missing in HW 7.5. It
is now corrected.
- Make sure to not forget the mass part in HW 7.1.
- In the hint part of 8.1, it is cosh^2(t)-sinh^2(t)=1. They are called hyperbolic
trigfunctions because r(t) = [cosh(t),sinh(t)] are on hyperbola, while
r(t)= [cos(t),sin(t)] is on a circle.
- Check out the page on computer algebra, especially
for checking identities or plotting stuff.