### Home > PC3 > Chapter 7 > Lesson 7.1.2 > Problem 7-25

7-25.

Christina is solving the equation *“That’s interesting,”* she says. *“Since **, this must mean that and . But that’s impossible.”*.

Why is it impossible?

What is the range of sine and cosine?

What is going on here?

Solve for

if*.*Using a calculator, evaluate

. There is another solution. Use the unit circle to help you calculate the second solution.