Question

find the exact value of the expression for the given value of θ

cos(2θ) if θ=pi/3

Answer 1

If you like degrees, then\[{\pi \over 3} = {60}^{\circ}\]

Answer 2

\[2\theta \implies 2\times 60 \implies 120\]

Answer 3

Can you find cos(120 degrees), or should I draw a triangle?

Answer 4

-0.5

Answer 5

i think i can find cos(120)

Answer 6

Good!

Answer 7

But in degrees, not radians.

Answer 8

i got 0.8142

Answer 9

Let me check it for myself!

Answer 10

@kizzfan911 You found the following:\[\cos(120 \text{ radians})\]But you have to find the following:\[\cos(\text{120 degrees)}\]

Answer 11

how do i find it in degrees instead of radians?

Answer 12

-.5 is what i got now. is that right?

Answer 13

Yes!

Answer 14

aight. thank you again.

Answer 15

You're welcome :)