Worksheets · Precalculus

Precalculus sum and difference identities worksheet

Any angle that is a sum or difference of the special ones can be worked out exactly, which is where values like sin 75 come from.

Select your difficulty

Pick more than one for a sheet that mixes them.

Free math worksheets at sigmaprep.io/worksheets© 2026 Sigma Prep

Sigma Prep · sigmaprep.io/worksheets

Name

Sum and Difference Identities

Date Period

Simplify each expression.

  1. cos⁡(225∘−30∘)
  2. sin⁡(270∘−30∘)
  3. sin⁡(225∘−30∘)
  4. sin⁡(270∘+30∘)
  5. sin⁡(150∘−45∘)
  6. sin⁡(315∘+30∘)
  7. sin⁡(135∘−60∘)
  8. sin⁡(210∘+45∘)
  9. cos⁡(45∘−150∘)
  10. cos⁡(210∘+60∘)
  11. cos⁡(60∘−135∘)
  12. sin⁡(210∘−45∘)
  13. sin⁡(45∘−120∘)
  14. cos⁡(45∘−210∘)
  15. cos⁡(45∘−120∘)
  16. sin⁡(330∘−30∘)
  17. sin⁡(45∘−150∘)
  18. cos⁡(300∘+45∘)
  19. sin⁡(60∘−135∘)
  20. sin⁡(210∘−60∘)

Free math worksheets at sigmaprep.io/worksheets© 2026 Sigma Prep

Sigma Prep · sigmaprep.io/worksheets

Name

Sum and Difference IdentitiesAnswer keyVersion 1

Date Period

Simplify each expression.

  1. cos⁡(225∘−30∘)−6+24
  2. sin⁡(270∘−30∘)−32
  3. sin⁡(225∘−30∘)−6−24
  4. sin⁡(270∘+30∘)−32
  5. sin⁡(150∘−45∘)6+24
  6. sin⁡(315∘+30∘)−6−24
  7. sin⁡(135∘−60∘)6+24
  8. sin⁡(210∘+45∘)−6+24
  9. cos⁡(45∘−150∘)−6−24
  10. cos⁡(210∘+60∘)0
  11. cos⁡(60∘−135∘)6−24
  12. sin⁡(210∘−45∘)6−24
  13. sin⁡(45∘−120∘)−6+24
  14. cos⁡(45∘−210∘)−6+24
  15. cos⁡(45∘−120∘)6−24
  16. sin⁡(330∘−30∘)−32
  17. sin⁡(45∘−150∘)−6+24
  18. cos⁡(300∘+45∘)6+24
  19. sin⁡(60∘−135∘)−6+24
  20. sin⁡(210∘−60∘)12

Free math worksheets at sigmaprep.io/worksheets© 2026 Sigma Prep

How to do these

sin⁡(45∘+30∘)

  1. This is the sum formula for sine.
  2. sin 45 cos 30 plus cos 45 sin 30.

The answer is sin⁡75∘.

Where students go wrong

Assuming sine distributes over addition. sin(A + B) is not sin A + sin B, and the formula exists precisely because the obvious thing is false.

Also called angle sum formulas or compound angle identities.

Questions about these worksheets

Yes. Every sum and difference identities sheet is free to print and free to download as a PDF. There is no account to make, no email to hand over and no limit on how many you take.

Yes. The answer key prints on a second page, and you can choose whether it shows each question beside its answer or just the answers in a list.

Yes. Print straight from the page, or download the PDF and print that. The sheet is laid out for paper rather than squeezed off a screen, so there is room to work under each question, and the answer key comes out on its own page.

Precalculus is usually taken around 11th or 12th grade, though schools vary and plenty of students meet it earlier or later. Pick the difficulty rather than the grade: the easy level suits a first lesson on it, the hard level suits review before a test.

Yes, as many as you like. The questions are built fresh each time rather than picked from a fixed set of files, so pressing Generate gives a new sheet. That is what you want for a second class, a retake, or two students sitting next to each other.

That is the closest comparison, and Kuta Software is good software. It is also paid software you install on a computer. These worksheets run in a browser tab for free, with no account and nothing to install. Like Kuta, the sum and difference identities questions are generated when you ask for them rather than pulled from a fixed set of files, so two classes never get the same sheet, and the answer key comes with it.

Yes. There are two levels, and you can tick more than one for a sheet that mixes them, in which case the questions come out easiest first. The harder levels are not just larger numbers: they ask for something the easy ones do not.

Assuming sine distributes over addition. sin(A + B) is not sin A + sin B, and the formula exists precisely because the obvious thing is false.