I would recommend "Introduction to Linear Algebra," by Gilbert Strang. It is a compact but very helpful textbook reference written by a well-known MIT professor. There is a corresponding online MIT course that is free, so that's a bonus. I am currently using it to study linear algebra with no class or previous experience, and I think it does a solid job of explaining things. Each section in the book has a set of questions for you to work through, and answers to selected questions appear in an appendix at the end of the book.
Hope this helps!
Answer:
Given: The radius of circle C is 6 units and the measure of central angle ACB is StartFraction pi Over 2 EndFraction radians.
What is the approximate area of the entire circle?
113 square units
What is the approximate area of the entire sector created by central angle ACB?
28 square units
What is the approximate area of the shaded region only?
22 square units
Nothing changes if you don't add anything.
Example:
10+10=20
20+0=20
nothing changes.