Worksheets · Geometry

Cofunction identities worksheet for Geometry

In Geometry the cofunction identities come straight from a right triangle: the two acute angles add to 90°, and the side opposite one is adjacent to the other. So the sine of one acute angle is the cosine of the other, which is why sin 30° and cos 60° are equal.

Also taught in Algebra 2 and Precalculus, each at its own level and with its own examples.

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Pick more than one for a sheet that mixes them.

The preview can look cramped on a phone. The PDF and printed sheet come out normal.

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

Sigma Prep · sigmaprep.io/worksheets

Name

Cofunction Identities

Date Period

Rewrite as a cofunction, or solve for the angle.

  1. Write cos⁡4∘ as a cofunction
  2. Write tan⁡7∘ as a cofunction
  3. Write sin⁡15∘ as a cofunction
  4. Write sec⁡43∘ as a cofunction
  5. Write cos⁡79∘ as a cofunction
  6. Write cot⁡85∘ as a cofunction
  7. Write sin⁡54∘ as a cofunction
  8. Write csc⁡28∘ as a cofunction
  9. Write sin⁡2∘ as a cofunction
  10. Write csc⁡87∘ as a cofunction
  11. Write cos⁡1∘ as a cofunction
  12. Write tan⁡17∘ as a cofunction
  13. Write sin⁡31∘ as a cofunction
  14. Write sec⁡79∘ as a cofunction
  15. Write cos⁡68∘ as a cofunction
  16. Write cot⁡60∘ as a cofunction
  17. Write sin⁡14∘ as a cofunction
  18. Write cot⁡74∘ as a cofunction
  19. Write cos⁡63∘ as a cofunction
  20. Write sec⁡70∘ as a cofunction

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

Sigma Prep · sigmaprep.io/worksheets

Name

Cofunction IdentitiesAnswer keyVersion 3

Date Period

Rewrite as a cofunction, or solve for the angle.

  1. Write cos⁡4∘ as a cofunctionsin⁡86∘
  2. Write tan⁡7∘ as a cofunctioncot⁡83∘
  3. Write sin⁡15∘ as a cofunctioncos⁡75∘
  4. Write sec⁡43∘ as a cofunctioncsc⁡47∘
  5. Write cos⁡79∘ as a cofunctionsin⁡11∘
  6. Write cot⁡85∘ as a cofunctiontan⁡5∘
  7. Write sin⁡54∘ as a cofunctioncos⁡36∘
  8. Write csc⁡28∘ as a cofunctionsec⁡62∘
  9. Write sin⁡2∘ as a cofunctioncos⁡88∘
  10. Write csc⁡87∘ as a cofunctionsec⁡3∘
  11. Write cos⁡1∘ as a cofunctionsin⁡89∘
  12. Write tan⁡17∘ as a cofunctioncot⁡73∘
  13. Write sin⁡31∘ as a cofunctioncos⁡59∘
  14. Write sec⁡79∘ as a cofunctioncsc⁡11∘
  15. Write cos⁡68∘ as a cofunctionsin⁡22∘
  16. Write cot⁡60∘ as a cofunctiontan⁡30∘
  17. Write sin⁡14∘ as a cofunctioncos⁡76∘
  18. Write cot⁡74∘ as a cofunctiontan⁡16∘
  19. Write cos⁡63∘ as a cofunctionsin⁡27∘
  20. Write sec⁡70∘ as a cofunctioncsc⁡20∘

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

How to do these

Write sec⁡35∘ as a cofunction

  1. The cofunction of secant is cosecant.
  2. The complement of 35° is 90° - 35° = 55°.

The answer is csc⁡55∘.

Where students go wrong

Expecting the identity to work for any two angles. sin A = cos B only when A and B are complementary, like the two acute angles of one right triangle.

Also called cofunctions, complementary angle identities or sin cos complementary.

Questions about these worksheets

Yes. Every cofunction 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.

Geometry is usually taken around 9th or 10th 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 cofunction 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.

Subtracting from 180 instead of 90. Cofunctions are about complementary angles; supplementary ones belong to a different identity.