Answer:

Step-by-step explanation:
Using the addition formulae for cosine
cos(x ± y) = cosxcosy ∓ sinxsiny
---------------------------------------------------------------
cos(120 + x) = cos120cosx - sin120sinx
= - cos60cosx - sin60sinx
= -
cosx -
sinx
squaring to obtain cos² (120 + x)
=
cos²x +
sinxcosx +
sin²x
--------------------------------------------------------------------
cos(120 - x) = cos120cosx + sin120sinx
= -cos60cosx + sin60sinx
= -
cosx +
sinx
squaring to obtain cos²(120 - x)
=
cos²x -
sinxcosx +
sin²x
--------------------------------------------------------------------------
Putting it all together
cos²x +
cos²x +
sinxcosx +
sin²x +
cos²x -
sinxcosx +
sin²x
= cos²x +
cos²x +
sin²x
=
cos²x +
sin²x
=
(cos²x + sin²x) = 
Answer:
x= -1; y= -2
Step-by-step explanation:
A: 6x+4y= -14
B: -x-5y=11
6B is : -6x-30y=66
A+6B is : -26y=52
so y= -2
so A becomes : 6x+4.(-2)= -14
so x= -1
Answer:
0.3
Step-by-step explanation:
Answer:
in grams 6 kilograms is equal to 6000 grams or 13.2276 pounds
multiply 6 by each number don't forget to do the zero's.
23. not equivalent because the first row 3x-9y=5 then if you multiplied this equation by 2 it will be 2(3x-9y) = 2(5) so 6x-18y= 10 not 6x-9y=10
24.equivalent because the second row 2y-6x=8 multiplied by 2 is 2(2y-6x)= 2(8) so 4y-12x=16
25. equivalent because the first row 5x+3y=19 multiplied by 2 is 2(5x+3y) = 2(19) SO 10X+6Y=38 and the second row 2x+4y=20 multiplied by 5 is 5(2x+4y)= 5(20) so 10x+20y=100