Question

Cos^2 20° - sin^2a - cos40°

Answer 1

Ответ: 0

Объяснение:

сos^2 20"-sin^2 20" -cos40"= (cos^2 20"-sin^2 20")-cos40"=cos40" -cos40"=0

Answer 2

Let's simplify the expression step by step:

1. Start with the given expression: cos^2(20°) - sin^2(a) - cos(40°).

2. Use the trigonometric identity cos(2θ) = cos^2(θ) - sin^2(θ) to simplify cos^2(20°): cos^2(20°) = 1/2 * [1 + cos(40°)].

3. Substitute this into the original expression: 1/2 * [1 + cos(40°)] - sin^2(a) - cos(40°).

4. Combine like terms by subtracting cos(40°) from both terms in the brackets: 1/2 * [1 - cos(40°)] - sin^2(a).

So, the simplified expression is: 1/2 * [1 - cos(40°)] - sin^2(a).