Question

cos(theta)= 1 when theta = n*pi, for n an integer...true or false

Answer 1

n is an integer, so say n = 0

theta = n*pi would then equal what?

Answer 2

this was the exact question out of my trig book.

Answer 3

theta = n*pi = 0*pi = 0

Answer 4

So when theta = 0, what is cos(theta)

Answer 5

1

Answer 6

if n = 1, then

theta = n*pi = 1*pi = pi

Answer 7

if n = 1, then theta = pi

if that's true, what is cos(theta)?

Answer 8

.1719

Answer 9

make sure you're in radian mode

Answer 10

i am...am i missing something?

Answer 11

cos(pi) is not 0.1719

Answer 12

-1

Answer 13

so if theta = pi, then cos(theta) = -1

Answer 14

go back to the original statement, is it true?

Answer 15

yes

Answer 16

but we've just shown that cos(theta) = -1

Answer 17

-1 is still an integer

Answer 18

but the original statement is cos(theta) = 1

Answer 19

where theta = n*pi

Answer 20

n is an integer

Answer 21

aha

Answer 22

thank you... im an idiot