Question

how to find cot 120
I know it is negative

Answer 1

split it into known angles

Answer 2

cos120/sin120 ?

Answer 3

yes ! cos/sin works too ^

Answer 4

looks good !

Answer 5

i would have done like this -

Answer 6

since the period of cot is 180, i can add/subtract 180 and the value will not change

cot(120) = cot(120-180) = cot(-60) = -cot(60) = -sqrt(3)/3

Answer 7

nice

Answer 8

If the period is 360 as for for sin and cos and we subtract or add 180 or 90
by how much will the value change

Answer 9

is it this logic as 90 is 1/4 th of 360 value would be 1/4 th

Answer 10

the value will NOT change only if we add/subtract the PERIOD of function.

Answer 11

adding/subtracting 90/180 etc is a different logic :
it comes directly from the angle sum/difference identities

Answer 12

for example :

sin(x+90) = sinx cos90 + cosx sin90
= sinx 0 + cosx 1
= cos x

Answer 13

ohkk :)

Answer 14

cot(x+90)=?

Answer 15

cot(x+90) = cos(x+90) / sin(x+90)
= -sinx / cosx
= -tan x

Answer 16

oh yes