More Lessons for High School Regents Exam

Math Worksheets

High School Math based on the topics required for the Regents Exam conducted by NYSED.

Cofunctions are pairs of trigonometric functions that have equal values when their arguments are complementary angles.

Sine and Cosine are cofunctions because \(\sin \theta = \cos \left( {90^\circ - \theta } \right)\)

Secant and Cosecant are cofunctions because \(\sec \theta = \csc \left( {90^\circ - \theta } \right)\)

Tangent and Cotangent are cofunctions because \(\tan \theta = \cot \left( {90^\circ - \theta } \right)\)

A function f is cofunction of a function g if f(A) = g(B) when A and B are complementary angles.

sin(A) = cos(B), if A + B = 90°

sec(A) = scs(B), if A + B = 90°

tan(A) = cot(B), if A + B = 90°

Cofunctions

What is a cofunction. Finding the cofunction. Using the cofunction relationship

This video explains the cofunction identities and how to determine cofunctions given a function value. Most cofunction values are verified on a calculator.

This video explains how to use cofunction identities to solve trigonometric equations.

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