Question

Please help!!


Which of the following are identities? Check all that apply.

A. sin(x+y)-sin(x-y)=2cosx siny
B. cos(x+y)+cos(x-y)=cos^2 x - sin^2 y
C. cos(x+y)+cos(x-y)=2cosx cosy
D. sin(x-pi)=-sinx

Answer 1

does the last one say = 2cosx + siny ?

Answer 2

or are you multiplying it

Answer 3

if it's multiplication, then A, C, and D are identities.

Answer 4

on C?

Answer 5

A and C

Answer 6

if there's no plus sign, then A, C, and D are identities

Answer 7

yes theyre right

Answer 8

k

Answer 9

ok that was great thanks

Answer 10

np

Answer 11

can you help me on another @blurbendy

Answer 12

ill try

Answer 13

ok cool

Answer 14

given sin x =3/5 and x is in quadrant 2, what is the value of tan(x/2)?

Answer 15

im getting - 1/3

Answer 16

ok i think thats right idk if its positive or negative though

Answer 17

we're in the second quadrant so tan(x/2) will be negative

Answer 18

oh ok that makes sense duh

Answer 19

yeah, trig messes with your head sometimes lol

Answer 20

got it cool
thanks alot for all your help

Answer 21

np