Trigonometric Identities
Videos and lessons with examples and solutions to help High School
Algebra 2 students learn about trigonometric identities.
Trigonometric Identities:
Identities are equations true for any value of the variable.
Since a right triangle drawn in the unit circle has a hypotenuse of length 1, we define the trigonometric identities x = cos(theta) and y = sin(theta).
In the same triangle, tan(theta)=x/y, so substituting we get tan(theta) = sin(theta)/cos(theta), the tangent identity.
Another key trigonometric identity sin2(theta) + cos2(theta) = 1 comes from using the unit circle and the Pythagorean Theorem.
Trigonometric Identities: How to Derive / Remember Them - Part 1 of 3.
Trigonometric Identities: How to Derive / Remember Them - Part 2 of 3.
Trigonometric Identities: How to Derive / Remember Them - Part 3 of 3.
Fundamental Trigonometric Identities
The reciprocal identities, quotient identities and the Pythagorean identities.
Trigonometric Identities
Deriving Trigonometric Identities from 3 Known Identities
You can use the free Mathway calculator and problem solver below to practice Algebra or other math topics. Try the given examples, or type in your own problem and check your answer with the step-by-step explanations.
Identities are equations true for any value of the variable.
Since a right triangle drawn in the unit circle has a hypotenuse of length 1, we define the trigonometric identities x = cos(theta) and y = sin(theta).
In the same triangle, tan(theta)=x/y, so substituting we get tan(theta) = sin(theta)/cos(theta), the tangent identity.
Another key trigonometric identity sin2(theta) + cos2(theta) = 1 comes from using the unit circle and the Pythagorean Theorem.
Trigonometric Identities: How to Derive / Remember Them - Part 1 of 3.
The reciprocal identities, quotient identities and the Pythagorean identities.
Trigonometric Identities
Rotate to landscape screen format on a mobile phone or small tablet to use the Mathway widget, a free math problem solver that answers your questions with step-by-step explanations.
You can use the free Mathway calculator and problem solver below to practice Algebra or other math topics. Try the given examples, or type in your own problem and check your answer with the step-by-step explanations.
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