Question

cos(-11pi/4)
sin(-11pi/4)

Answer 1

\[\cos(a+k2\pi)=\cos(a) \]\[\sin(a+k2\pi)=\sin(a) \] for all integers k

Answer 2

So basically you can factor out multiples of 2 pi

Answer 3

yeah, i tried that i thought the exact value of cos what square root 3 and sin was 1/2

Answer 4

are you asking\[\cos(-11\frac{ \pi }{ 4 })\]or\[\cos(\frac{ -11\pi }{ 4 })\]

Answer 5

-11pi/4

Answer 6

That doesn't clarify. Is it (-11 pi)/4
or
-11 (pi/4)

Answer 7

(-11 pi)/4

Answer 8

So you subtract 2pi from that and what do you get?

Answer 9

Sorry add 2pi

Answer 10

13pi/4

Answer 11

\[\frac{ -11\pi }{ 4 }+2\pi=\frac{ -11\pi }{ 4 }+\frac{ 8 \pi }{ 4 }=\frac{ -3 \pi }{ 4 }\]

Answer 12

These are some values to remember:\[\cos (\pi/4)=\sin (\pi/4)=\frac{ \sqrt{2} }{ 2 }\] so that is for a 45 degree angle in quadrant I

Answer 13

Which quadrant does (-3/4)pi lie in?