In this book I'm reading, there are three problems I'm having a hard time with.

1.

When I enter on my TI-84+ and hit Enter, I get 7.745966692 instead.

2.

When I enter on my TI-84+ and hit Enter, I get 48, so that answer agrees with the book.

3.

When I enter on my TI-84+ and hit Enter, I get 84.85281374 instead.

Can anybody explain why my answer is different and what the book's answer means?

Roger