Simplify cos(pi/9)^2-sin(pi/9)^2

Problem

cos2(π/9)−sin2(π/9)

Solution

1. Identify the trigonometric identity for the double angle of cosine, which states cos(2*θ)=cos2(θ)−sin2(θ)

2. Substitute the value θ=π/9 into the identity.

3. Multiply the angle by 2 to find the simplified argument.

4. Simplify the resulting expression.

Final Answer

cos2(π/9)−sin2(π/9)=cos((2*π)/9)

Want more problems? Check here!