Question

Use a special triangle on the unit circle to determine the value of cos π/ 4 .

A) 1

B) 1 /2

C) √2/ 2

D) √2 /3

Answer 1

Do you know what a unit circle is?

Answer 2

\(\dfrac{\pi}{4}\) is in radians but it's equal to 45 degrees

Answer 3

If the hypotenuse is 1,

what are the two legs of the triangle?

You can use Pythagorean theorem to calculate the value of 'x'

since both angles are 45 that means they both have the same length

Answer 4

if you don't want to do all that work, you can just look at the unit circle I attached and see what the value of cos(pi/4) is

Answer 5

I believe it is C?

Answer 6

That is correct

Answer 7

Thank you

Answer 8

You're welcome!