Question

Evaluate. Write your answer in simplified, rationalized form. Do not round.

Answer 1

Answer:

  cos(45°) = (√2)/2

Step-by-step explanation:

The cosine of 45° is the x-coordinate of the point on the unit circle where the line y=x intersects it. That is, it is the positive solution to the equation ...

  x^2 +x^2 = 1

  x^2 = 1/2 = 2/4 . . . . . collect terms, divide by 2, express the fraction with a square denominator

  x = √(2/4) . . . . . . take the square root

  x = (√2)/2 . . . . . simplify

The cosine of 45° is (√2)/2.