Question

How do you solve the equation `costheta=-0.19` for `0<theta<2pi`?

Answer 1

`100^@95, 259^@05`

Explanation:

Calculator gives:
cos t = - 0.19 --> `t = 100^@95`
Trig unit circle gives another arc (angle) that has the same cos value:
`t = - 100.95^@, or t = 360 - 100.95 = 259^@05`
Answers for (0, 360):
`100.95^@, 259^@05`