Question

cos870° - sin780° = _____

-sq.root 3
sq. root 3
0

Answer 1

cos (870) = cos (150) = - sqrt(3)/2
sin (780) = sin (60) = sqrt(3)/2

So, -sqrt(3)/2 - sqrt (3)/2 = -2sqrt(3)/2 = - sqrt(3)

Note: an angle of 870 = an angle of 150, because every 360 it is periodic.

Answer 2

thank you so much!
what about this one??
sin400° = _____

-sin40°
sin40° <-- would it be this?
sin(-40)°

Answer 3

@Easyaspi314

Answer 4

sin (400) = sin (40)

Just subtract 360 from 400.

Both angles are identical.

Answer 5

And you can easily verify this on your calculator:

sin(400) = .6427876097
sin (40) = .6427876097

Answer 6

so it would be the answer i chose right??

Answer 7

Yes the answer you have indicated is the correct one.