Trigonometric Identities

Flashcards for basic trigonometric identities.

Sin(2x) = some unit circle thing

1) Find the two angles, for example, 5pi/4 and 7pi/4 equals 2x.

2) divide angles by 2 for 5pi/8, and 7pi/8.

3) add the period over two to the new angles

Trig identities

Image

When taking the root of a sin function

plus or minus, remember it’s a root. Also extraneous solutions if needed

Cosx = 1 when

x is 0 or 180 degrees for -1

Sinx = 1 when

X is 90 or 270 degrees for -1

Solving trig equations

Use trig identities to make same trig function

U can also divide something on both sides to get 1

Sin theta = 0

At 0 and pi

Sin2x when getting solutions do a 2nd period after dividing by 2