Final answer:
The double angle identities in trigonometry are sin(2θ) = 2sin(θ)cos(θ), cos(2θ) = cos²(θ) - sin²(θ), tan(2θ) = 2tan(θ) / (1 - tan²(θ)), and cot(2θ) = (cot²(θ) - 1) / 2cot(θ). They allow us to express the sine, cosine, tangent, and cotangent of double angles in terms of the sine, cosine, and tangent of single angles.
Step-by-step explanation:
The double angle identities in trigonometry are:
- sin(2θ) = 2sin(θ)cos(θ)
- cos(2θ) = cos²(θ) - sin²(θ)
- tan(2θ) = 2tan(θ) / (1 - tan²(θ))
- cot(2θ) = (cot²(θ) - 1) / 2cot(θ)
These formulas allow us to express the sine, cosine, tangent, and cotangent of double angles in terms of the sine, cosine, and tangent of single angles. By knowing the values of the single angle, we can easily calculate the values of the double angle using these identities.