Table of contents
- 0. Fundamental Concepts of Algebra3h 29m
- 1. Equations and Inequalities3h 27m
- 2. Graphs1h 43m
- 3. Functions & Graphs2h 17m
- 4. Polynomial Functions1h 54m
- 5. Rational Functions1h 23m
- 6. Exponential and Logarithmic Functions2h 28m
- 7. Measuring Angles40m
- 8. Trigonometric Functions on Right Triangles2h 5m
- 9. Unit Circle1h 19m
- 10. Graphing Trigonometric Functions1h 19m
- 11. Inverse Trigonometric Functions and Basic Trig Equations1h 41m
- 12. Trigonometric Identities 2h 34m
- 13. Non-Right Triangles1h 38m
- 14. Vectors2h 25m
- 15. Polar Equations2h 5m
- 16. Parametric Equations1h 6m
- 17. Graphing Complex Numbers1h 7m
- 18. Systems of Equations and Matrices3h 6m
- 19. Conic Sections2h 36m
- 20. Sequences, Series & Induction1h 15m
- 21. Combinatorics and Probability1h 45m
- 22. Limits & Continuity1h 49m
- 23. Intro to Derivatives & Area Under the Curve2h 9m
8. Trigonometric Functions on Right Triangles
Cofunctions of Complementary Angles
Struggling with Precalculus?
Join thousands of students who trust us to help them ace their exams!Watch the first videoMultiple Choice
Write the expression in terms of the appropriate cofunction.
cot(25°)
A
tan(65°)
B
tan(25°)
C
cot(65°)
D
cot(25°)

1
Understand the concept of cofunctions: Cofunctions are pairs of trigonometric functions that are complementary, meaning their angles add up to 90 degrees. For example, the cofunction of cotangent is tangent.
Identify the angle given in the problem: The angle provided is 25 degrees, and we need to find its cofunction.
Determine the complementary angle: Since cofunctions are based on complementary angles, calculate the complementary angle by subtracting the given angle from 90 degrees. So, 90° - 25° = 65°.
Relate cotangent to its cofunction: The cofunction of cotangent is tangent. Therefore, cot(25°) can be expressed in terms of its cofunction as tan(65°).
Verify the options provided: Among the options given, tan(65°) is the correct expression in terms of the cofunction of cot(25°).
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