Trigonometry: Identities & Functions

Question 1

sin θ

Accepted Answer

Opposite / Hypotenuse (SOH)

Question 2

cos θ

Accepted Answer

Adjacent / Hypotenuse (CAH)

Question 3

tan θ

Accepted Answer

Opposite / Adjacent (TOA); also sin θ / cos θ

Question 4

Pythagorean Identity

Accepted Answer

sin²θ + cos²θ = 1

Question 5

sin(0°)

Accepted Answer

0

Question 6

sin(30°)

Accepted Answer

1/2

Question 7

sin(45°)

Accepted Answer

√2/2

Question 8

sin(60°)

Accepted Answer

√3/2

Question 9

sin(90°)

Accepted Answer

1

Question 10

cos(0°)

Accepted Answer

1

Question 11

cos(60°)

Accepted Answer

1/2

Question 12

cos(90°)

Accepted Answer

0

Question 13

Reciprocal: csc θ

Accepted Answer

1/sin θ (cosecant)

Question 14

Reciprocal: sec θ

Accepted Answer

1/cos θ (secant)

Question 15

Reciprocal: cot θ

Accepted Answer

1/tan θ = cos θ/sin θ (cotangent)

Question 16

Double Angle: sin(2θ)

Accepted Answer

2 sin θ cos θ

Question 17

Double Angle: cos(2θ)

Accepted Answer

cos²θ - sin²θ = 2cos²θ - 1 = 1 - 2sin²θ

Question 18

Law of Sines

Accepted Answer

a/sin A = b/sin B = c/sin C

Question 19

Law of Cosines

Accepted Answer

c² = a² + b² - 2ab cos C

Question 20

Radian

Accepted Answer

Angle measure where arc length equals radius; 2π radians = 360°

Question 21

Unit Circle

Accepted Answer

Circle with radius 1 centered at origin; coordinates give (cos θ, sin θ)

Question 22

Period of sin/cos

Accepted Answer

2π radians (360°)

Question 23

Period of tan

Accepted Answer

π radians (180°)

Question 24

Amplitude

Accepted Answer

Half the distance between max and min values of a sinusoidal function

Trigonometry: Identities & Functions

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