Sin(150 + x)+ sin(150 − x) = cos x

Below.

Step-by-step explanation:

We need to prove this identity by taking the left  side and trying to transform it to the right side.

LHS = sin(150 + x) + sin(150 − x)

= sin 150 cos x + sin x cos 150 + sin 150 cos x - sin x cos 150

=  2 sin 150 cos x

= 2 * 1/2 * cos x

= cos x = RHS.

So it is proved.

i can answer this question sweetie!

step-by-step explanation:

a 4/6 = 9/12   not proportional

step-by-step explanation:

to find which are not proportional, we can use cross products

if it is true, they are proportional.   if it is not true, they are not proportional.

a 4/6 = 9/12

4* 12 = 6*9

48 = 54

not this is not proportional  

b 2/3 = 12/18  

2* 18 = 3 * 12

36 = 36

this is proportional

c 5/4 = 10/8  

5*8 = 4*10

40 = 40

this is proportional

d 7/5 = 35/25

7*25 = 5 * 35

175 = 175

is proportional