Trigonometric Identities - Concept

Concept Concept (1)

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 identies 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.

Sample Sample Problems (3)

Need help with "Trigonometric Identities" problems? Watch expert teachers solve similar problems to develop your skills.

Trigonometric Identities - Problem 1
Problem 1
How to use the Pythagorean identity to find cosine and tangent when sine is known.
Trigonometric Identities - Problem 2
Problem 2
How to use the unit circle to show that cosine is an even function, and sine and tangent are odd functions.
Trigonometric Identities - Problem 3
Problem 3
How to use the unit circle to show that sine and cosine have period 2*pi, and tangent has period pi.
© 2018 Brightstorm, Inc. All Rights Reserved. Terms · Privacy