Question

sin(21pi/4)????

Answer 1

what r u asking

Answer 2

simplify, not the exact value though

Answer 3

okay what does pi stand for

Answer 4

hello???

Answer 5

the answer is either sin(5pi/4), sin(3pi/4), sin(7pi/4) or sin(pi/4)

Answer 6

5 1/4

Answer 7

pi stands for 180 degrees

Answer 8

idk thats what i got let me do it again and if this is a test then do the other questions while i work it out

Answer 9

ok

Answer 10

i think its 3pi/4

Answer 11

hello??

Answer 12

i got sin(5pi/4)

Answer 13

there are multiple answers.

The first thing you want to do is to kind the angle in the same place as 21π/4 on the unit circle by subtract 2π until you get it. That looks like how @Tamara7301 got 5π/4.

5π/4 is in the third quadrant on your unit circle. sin Θ is also negative in the 4th quadrant. The fourth quadrant angle is (2π - π/4) = 7π/4

Answer 14

no thats not what i got

Answer 15

idk

Answer 16

idk i hope i helped if not i am really sorry but i have to go

Answer 17

thanks for trying

Answer 18

welcx

Answer 19

what quadrant am i trying to get it in?

Answer 20

no clue (

Answer 21

sorry

Answer 22

@peachpi?

Answer 23

how many more min till the test ends

Answer 24

theres not a time limit

Answer 25

If all your question is asking is to find an equal value to sin(21π/4), they're both valid. The question would have to give you some other info to restrict the quadrant otherwise

Answer 26

huh??????????????

Answer 27

it doesnt give me any more info. which answer do you think would most likely be correct?

Answer 28

go with 5π/4, it's at least in the same quadrant

Answer 29

i also have the same question for cos and tan

Answer 30

cos(21pi/4) and tan21pi/4)

Answer 31

It would be 5π/4 for all of those.
It looks like they're trying to get to to realize that 21π/4 and 5π/4 are exactly the same angle.
21π/4 just went around the circle two more times.
\[\frac{ 5\pi }{ 4 }+2\pi+2\pi=\frac{ 21\pi }{ 4 }\]